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View Full Version : Carb Jetting 101: Terms, Tips and Jetting Theory



Dammit!
07-11-2006, 10:38 PM
A jetting sticky thread is long overdue so here goes.

Resident experts, help me out here. If you spot a typo or something I'm just flat wrong about, let me know or if you have some useful info, post it. Just keep it as newbie friendly as possible. The subject matter is confusing enough on it's own. I'll be adding to/editing the original post as needed.

If you need a service manual, you can download one for most models here (http://www.3wheelerworldforums.com/showthread.php?t=56218).

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Terms and Definitions

Jetting: The term comes from the two main circuits that control fuel flow in a carburetor. The pilot jet and the main jet.

Main Jet: This is the main fuel circuit in a carburetor. It's a common misconception that this circuit only effects engine performance at wide open throttle. The main jet actually has a trickle down effect on other adjustments and should be adjusted first.

Needle: The needle is attached to the carb slide and is raised and lowered when you push and release the throttle. When you let off your throttle, the needle lowers into the main jet circuit, cutting off fuel flow as it goes down.

Needle Clip: This is the small circular clip that is used to adjust the needle position.

Pilot Jet: This is second jet in your carb. Much smaller than the Main Jet and typically has no effect beyond approximately 1/4 throttle. It's used to adjust your mixture at idle and low throttle.

Air/Pilot Screw: The air screw works in combination with the pilot jet. You can consider it a fine tuner for the pilot circuit. It's most obvious effect is noticed by throttle response.

Float: The float controls fuel level in the float bowl at the bottom of the carburetor. It has no effect on jetting but can cause some symptoms that can be easily confused with a jetting problem. If the fuel level is too low for example, it can cause a bog similar to a lean condition.

Float Seat/Valve: Basically the valve that stops fuel from flowing into the float bowl when the float reaches a specified level.

Rich: A "rich" condition is what occurs when you have too much fuel in your fuel/air mixture. Symptoms of a rich condition can be a rough running engine (sputtering), a black spark plug, a wet plug or excessive plug fouling.

Lean: A "lean" condition is what occurs when you have insufficient fuel in your mixture creating an over abundance of oxygen. Symptoms can be a rough running engine (bogging), a white or light gray spark plug and sometimes can result in overheating or even severe engine damage.

Sputtering: This isn't exactly a technical term but is commonly used to describe how an engine runs when jetted too rich. For example, using too large of a main jet will cause more fuel to enter the combustion chamber than it can efficiently burn. This will result in a "sputter" at full throttle. It could best be described as a rapid misfire. Note: a rich condition is not the only possible source of this type of problem.

Bogging: Again, not a technical term but commonly used. Bogging can be a result of a lean setting where not enough fuel is entering the combustion chamber for the motor to run properly. In some instances this can cause the machine to "bog" as if it were actually running out of gas. Note: a lean condition is not the only possible source of this type of problem.

WOT: This an acronym that stands for Wide Open Throttle.

Plug Chop: Plug chops are the most accurate and easiest way to check your jetting. A proper plug chop should be done with a clean spark plug. Example; to check your main jet, put in a clean spark plug and run the trike at Wide Open Throttle (WOT) for several seconds, then in one motion, pull in the clutch (if applicable), kill the engine and let off the throttle. Remove the spark plug and check the color (refer to chart in this thread).

Float: The float controls fuel level in the float bowl at the bottom of the carburetor. It has no effect on jetting but can cause some symptoms that can be easily confused with a jetting problem. If the fuel level is too low for example, it can cause a bog similar to a lean condition.

Float Seat/Valve: Basically the valve that stops fuel from flowing into the float bowl when the float reaches a specified level. If worn it can cause the float bowl to overflow.

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Nobody can tell you exactly what jets to use!

This is especially true with these 20 year old trikes. No two are exactly alike. Different mods, various states of mechanical well being and different locations (altitude, humidity etc) all play a part. Something as simple as removing your airbox lid can have an effect on your jetting. This is why it's critical that you understand how jetting works so you can get it dialed in perfectly for YOUR machine and riding conditions.


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Proper Jetting Procedure

The first step is to get your Main Jet dialed in. This circuit should be done first because it has a trickle down effect.

The Main Jet effects your performance most noticably at WOT. You do not fix a low throttle problem by changing your main jet. When the main is correct, there should be no sputtering or bogging at WOT.

Other than performance, the way to test your main jet is by doing WOT Plug Chops. The color of the plug will tell you if you need to do any fine tuning. DO NOT assume it is correct just because the engine appears to be running good. Remember, white and light gray is LEAN which means you need a larger main jet. Black and wet is rich which requires a smaller main jet. The target is a nice tan color. For a much more in depth explanation of plug reading and pictures, click here! (http://www.maxracesoftware.com/spark_plugs.htm)

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After your main jet is dialed in, it's time to move on to the needle.

The Needle effects performance from approximately 1/4 throttle to 2/3 throttle. If you're experiencing performance issues in this throttle range but your main jet is correct, this is where you fix it.

To adjust the needle richer(more fuel), you need to raise it up out of the main jet. You accomplish this by lowering your needle clip. This allows more fuel to flow from the main jet by raising it out of that circuit earlier in the throttle's range of motion. It will make sense once you take a good look at it.

To adjust the needle leaner (less fuel), you need to raise your needle clip. This leaves the needle in the main jet circuit longer, allowing less fuel to flow past.

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Now it's time to adjust the pilot jet and air screw.

This is how I adjust my pilot jet. If anyone has a better technique, chime in.

If the engine does not quickly return to idle after a good rev, it's too lean and needs a bigger pilot jet. If there's bogging when taking off or reving from idle, it's too rich. These problems can often be tuned out with the air screw.

There's a couple techniques for the pilot/air screw. One that I've heard is to set the idle somewhat high, tighten the air screw until the motor starts to die, then loosen it until it starts to die again, then set the screw right in the middle between these two points, then adjust the idle. I haven't tried that technique, personally.

The way I do it is basically by checking off idle throttle response. Adjust it both ways until you get a clean response when you stab the throttle.

When adjusting the air screw, tightening the screw is richer and loosening it is leaner. This is because tightening the screw allows less air to pass (resulting in more fuel in the mixture which = richer), loosening it lets more air through. Edit: depending on the carb, it's possible that this adjustment might be the opposite. Some experimentation will show you which way does what. The type above is the most common with 3 wheelers.


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Symptoms and Solutions

My bike is breaking up on the top end. What's wrong?
That could be a sign of too rich of a main jet. You need to do a WOT plug chop to be sure because an electrical problem can cause a similar symptom. If the plug is black and/or wet, you're too rich. Drop a couple sizes down and try again.

I have no or very little power on the bottom end. It's bogging out a little but once I get past mid-throttle and over it seems fine.
Check your needle setting. If it's bogging a little until about 2/3 throttle, richen it up a little by lowering your needle clip. If the problem gets worse, go two clips in the opposite direction and see if it improves.

My bike is running fine but it won't idle no matter what I do with the idle screw. Should I change the pilot?
Try adjusting the air screw before you go tearing into the carb to change the pilot jet. The stock pilot size should get you close enough to fine tune it with the air screw for most applications. The pilot jet can also become clogged. In which case it needs to be removed and thoroughly cleaned out or simply replaced.

My trike is cutting out every couple of seconds under throttle. The faster I go, the shorter the intervals between drop outs.
This is most likely a float adjustment issue and has nothing to do with your jetting. The float level could be low, causing the engine to die out for a second while the bowl fills back up. Adjust your float to attain a higher fuel level in the float bowl.

How do I know where to start with my main jet?!
When in doubt, go rich! You can make an educated guess by looking at what the stock jet size is, then taking into account what kind of mods you have. If you have an aftermarket pipe and filter, you're going to be flowing a lot more air through the engine than if those items were stock so you have to richen up the jetting to match that increased oxygen. In my opinion it's always best to go richer than you think is really needed, then jet down. Jet it rich until it sputters at WOT, then go down until it stops sputtering, then check the plug for piece of mind. This technique is especially useful in situations where you do not get good readings from your plug (which can be caused by a number of factors). This is my primary method of getting my main jet dialed in.

When I'm climbing a steep hill or dune, I hear a little bit of a pinging sound. What is that?
That is called detonation. This happens when you need to run a higher octane fuel. Under that kind of load, your engine is generating more heat which can cause lower octane fuel to ignite earlier than it's supposed to. It is not a jetting issue.

3Razors
07-11-2006, 11:33 PM
Good info for anyone out there. Careful with checking the plug sometimes you can get a false reading depending on the fuel or few minutes with a warm motor at idle or slow speed will darken a plug and the mixture can still be dangerously lean at the torque peak. There is only one way to know what is rich: that is make it too rich! Jet it up to the point where it blubbers and misfires at wide open throttle (say 3rd or 4th gear). Then you can lean it down a little at a time until it runs clean. Do the same at half throttle, with the needle position.

Also stick with genuine mikuni or keihin jets. The aftermarket jets do not have the same precision tolerences, and can really make a jetting nightmare.

ditchmud
07-12-2006, 12:14 AM
Good topic, carb tuning can be a trick, but when you get it right it'll make all the difference in the world. I have some real good info that was discussed in another web group that I belong to for my street bike. I posted a question for some help jetting my carbs, and recieved a lot of good intruction including some diagrams that made everything click and I wish I knew how to send it to this thread but I do not, sorry! BUt if you want to check this info out it is at the following web group address http://autos.group.yahoo.com/group/KAWASAKI_KZmessages the conversation started with my post on june 5 of this year,and continues with the other members replies. I hope you go and check it out it's some awesome information I just don't know how to get it sent here, maybe someone else has the know how to get it attached to this thread

Dammit!
07-12-2006, 12:28 AM
Good topic, carb tuning can be a trick, but when you get it right it'll make all the difference in the world. I have some real good info that was discussed in another web group that I belong to for my street bike. I posted a question for some help jetting my carbs, and recieved a lot of good intruction including some diagrams that made everything click and I wish I knew how to send it to this thread but I do not, sorry! BUt if you want to check this info out it is at the following web group address http://autos.group.yahoo.com/group/KAWASAKI_KZmessages the conversation started with my post on june 5 of this year,and continues with the other members replies. I hope you go and check it out it's some awesome information I just don't know how to get it sent here, maybe someone else has the know how to get it attached to this thread

That link doesn't work for me.

smokinp
07-19-2006, 01:06 AM
Good read up:beer

crackshot
07-19-2006, 08:54 AM
yep good read. Worth making it a sticky.

85hondaatc125m
07-22-2006, 02:34 PM
I have a question about jetting that I didnt see up there. About the cold wether, would replacing your jet for cold weather help it run. My trike is always dieing in -10 temperatures and I was wondering if a bigger jet would let me ride in the coldness?And another question too. In my manual it says that stock my trike came with a no.92 jet, it then says for going 5000feet+ you need a no. 88 jet. Are those numbers the size of the jet? or are they just a factory product number. If they are the sizes of the jet would a 92 jet be bigger than an 88 jet or the other way around. Sorry for all of the questions Thanks

team-red-rider
07-22-2006, 03:35 PM
92 is the size and it is also bigger!

Dammit!
08-01-2006, 12:47 AM
I have a question about jetting that I didnt see up there. About the cold wether, would replacing your jet for cold weather help it run. My trike is always dieing in -10 temperatures and I was wondering if a bigger jet would let me ride in the coldness?And another question too. In my manual it says that stock my trike came with a no.92 jet, it then says for going 5000feet+ you need a no. 88 jet. Are those numbers the size of the jet? or are they just a factory product number. If they are the sizes of the jet would a 92 jet be bigger than an 88 jet or the other way around. Sorry for all of the questions Thanks


You should jet richer in extreme cold temperatures, yes.

Yes, those are the actual jet sizes and the bigger the number, the richer the jet.

Frankencelery
08-15-2006, 12:25 AM
Wow, awesome info! I put an aftermarket carb from Beatrice Cycle on my 200s, and it's always been horrible at low throttle. Admittedly, I've never adjusted the pilot screw, because its in such a terrible place I haven't been able to get to it. But I was thinking I needed a bigger main jet until I read Dammit's tips. Now I know it's probably the pilot screw or the clip position that will get me power at the bottom end. I'll let you know.

Dammit!
08-15-2006, 11:09 AM
Could be a clogged up pilot jet too. The opening is very small and doesn't take much to block it.

Frankencelery
08-15-2006, 08:21 PM
I don't think so, because it was that way from the time it was brand new. I'll mess with it tonight and we'll find out.

Billy Golightly
08-26-2006, 05:50 PM
I just got done leaning out the main in my new 250R. It had a 175 in it and blubbered badly. I installed a 168 and it runs much better now. However it has a little bit of an oddity. When I short shift the engine and lug it where it has more of a load it runs "cleaner" then it does say I put it in first gear and hold the throttle wide open or during a 1st/2nd gear wheelie after the engine gets up to higher RPMs. Still a little rich?

Dammit!
08-26-2006, 06:58 PM
I just got done leaning out the main in my new 250R. It had a 175 in it and blubbered badly. I installed a 168 and it runs much better now. However it has a little bit of an oddity. When I short shift the engine and lug it where it has more of a load it runs "cleaner" then it does say I put it in first gear and hold the throttle wide open or during a 1st/2nd gear wheelie after the engine gets up to higher RPMs. Still a little rich?

Could be. Mine used to do something a little similar after the last top end rebuild. All I had to do was ditch the airbox lid (which I don't need out here anyway) and it cleared it up.

How's your plug looking?

Billy Golightly
08-26-2006, 07:31 PM
I pulled the plug after a full throttle run, turned it off and coasted into the shop. Porcelin was still dark, the bridge looked a little on the lean side (had some white on it). The porcelin was probably dark from me riding it earlier because I did not change the plug for just the chop run. So I put a 170 in it, and went down one notch on the needle. The mid range feels about perfect now but the top is still really boggy. I'll probably try putting the 168 back in tomorrow.

Mr. Sandman
09-01-2006, 01:32 PM
Excellent info Dammit! I'd like to add how to do a proper plug chop as I see that question and misinformation all the time. Just remember, plug chops are done to determine main jetting only.

1. Use a new plug, clean air filter and have your bike, trike or quad warmed up to the proper operating temperature.
2. Make a WOT pass through at least 5th gear. What's WOT? Go back and re-read Dammit's first post.
3. Doing all four at the same time, hit the kill switch, let off the throttle, pull in the clutch and roll to a stop. (Rolling out anytime without pulling in the clutch could cause a seizure as the piston will continue at high RPM through it's stroke without pre-mix lubrication and it'll overheat and seize in a hurry. Running out of gas will do the same thing).
4. Pull the plug and read it. The porcelain insulator should be a nice cocoa brown, not on or near the tip, but down inside the plug. If it's still white or light in color you're running too lean and if it's black and or oily your running too rich. Re-jet, go back to step one and start over.

chris200x
09-01-2006, 01:37 PM
Excellent info Dammit! I'd like to add how to do a proper plug chop as I see that question and misinformation all the time.

1. Use a new plug, clean air filter and have your bike, trike or quad warmed up to the proper operating temperature.
2. Make a WOT pass through at least 5th gear. What's WOT? Go back and re-read Dammit's first post.
3. Doing all four at the same time, hit the kill switch, let off the throttle, pull in the clutch and roll to a stop. (Rolling out anytime without pulling in the clutch could cause a seizure as the piston will continue at high RPM through it's stroke without pre-mix lubrication and it'll overheat and seize in a hurry. Running out of gas will do the same thing).
4. Pull the plug and read it. The porcelain insulator should be a nice cocoa brown, not on or near the tip, but down inside the plug. If it's still white or light in color you're running too lean and if it's black and or oily your running too rich. Re-jet, go back to step one and start over.

Thank you! :beer

I'm having a heck of a time right now trying to figure this out. This was the specific info I needed.

3Razors
09-12-2006, 03:07 AM
I stumbled upon this page from Duncan racing for Keihin carbs. Has some very useful info. on the needle part of jetting.

http://www.duncanracing.com/techfaq/Tech_keihin-carburetion-jetting.phtml

Sargon2112
09-19-2006, 04:52 PM
If I might add one suggestion: When tweaking / dialing your carb in, make one change at a time... especially if you don't have much jetting experience. That way, if the change you made has an effect (good or bad), you'll know what and most importantly, you'll know 'why'.

Great thread!!

Billy Golightly
09-19-2006, 07:26 PM
I also would like to add (From personal experience in the last day and a half) if you've got a 2 stroke motor that just will NOT clean out and smokes like a fiend, check your crank seals. Transmission oil level will also more then likely be going down as well too.

erectordale
10-15-2006, 08:49 PM
OK you carb pro's I have a 500cc with a bing 55 runs great and the plug chops show its jetted correctly It's impossible too kick start with out priming shoot a sqirt of fuel in the carb she starts right up. where Am I going wrong here??? we have just been pull starting it. it takes about 30 feet too get it started

TtownJoeShow
10-17-2006, 07:51 AM
I have a question too, my base ring doesn't get any color change! it stays looking new...BUT where the threads are gets black and the porcillan does a little too. the ground strap goes half black (maybe alittle less) the other half goes alittle yellow/ gray...the side of the ground strap goes fairly yellow. there is no aluminum specs, nore is the electrode ditch getting filled....the 85 atc 250R runs exellent, maybe alittle too zingy tho (FMF Fatty w/Powercore, BRV and Uni, only mods) running a BR8ES 300ft above sea leval @ 10oC and 40:1 Amsoil synthetic, 91-93 octane
Jets are: Main 140
Pilot 52
Needle 28V
Air Screw think it was 1 3/8 turns out grr
i did 4 chops, played witht he screw after 1st, did mental note the turns but well that didn't take lol DAMN!

I ordered jets and they should b in today or tomorw (142-180)

Would i be right by saying it needs a 145 or 142 main?

Dammit!
10-17-2006, 11:12 AM
Ttownjoeshow: it's impossible to jet over the internet. All I can say is a 140 main SEEMS like it would be too small for what you're running. Stock is 142 and you're running an aftermarket pipe and filter which should give you substantially better air flow than stock so 90% of the time you would need to jet richer to compensate.

Dale: Is the plug dry after you try to kickstart it? Might want to try a bigger pilot if it is.

erectordale
10-17-2006, 08:07 PM
the plug looks dry when trying too kick it over I have a larger pilot and will try that thanks

TtownJoeShow
10-19-2006, 07:13 PM
k so i need something cleared up.... By Soot, is that blck or grey?
Should the ground strap be a 2 tone brown?


all i'm getting is black on the ring, well on one a light black almost dark brown.
The ground strap, some black, then closer to the end grey and on one or two sides some yellow
Thanks a million in advance!

i got it! soot can b black and grey! ground strap can b brown black and grey!

now i think black is rich, grey is atad lean and brown is good...

don250r
11-11-2006, 03:28 PM
i've noticed over the years, that when people add multi-stage reeds(thru power reeds, a RAD valve, or ESR valve.etc.).
They don't follow instructions!
9 times out of 10, the trike is over-jetted on the main(due to increased air-flow).
when installing ANY of the above mods, remember to DROP the main jet 1-3 sizes, depending on the plug-chop(its in the instructions).

On a side-bar........
I'm not sure, Mr Sandman, but can plug-chops also help to determine correct needle height after the main is jetted in?
Following plug-chop instructions, but at half throttle.
Hope any of this helps anybody out there.

Rustytinhorn
02-02-2007, 09:50 PM
I am not asking what size jet to run...but trying to trouble shoot my bike and was wondering what size jet others run at my elevation cuz mine is sputterin BIG time.
(I pulled plug and it looks rich, but bear with me and answer my question) Thanks
elevation: 5280 feet
main jet: 142
idle 'r pilot: 60

2sprman2
03-12-2007, 02:33 PM
How do you raise your needle clip?

Dammit!
03-14-2007, 02:11 PM
How do you raise your needle clip?

It's pretty obvious once you get it apart. Pull the clip off the needle and put it in a different slot (there's typically five positions).

edog
03-28-2007, 10:31 PM
Well Dammit your thread has been very helpfull.

Thanks

Eric

Bryan Raffa
03-29-2007, 08:29 AM
this is a spark plug with the threds cut off I have found this verry use full to find out how the bike is jetted.. for a long time I was only lookin at the verry tip of the plug for jetting.. this is where I look for proper jetting color.. hope this helps you guys...:D

Ttown it sounds like your lean at idle and ritch at your mid range

TtownJoeShow
03-30-2007, 04:47 AM
lol its interesting! this jetting thing i mean...my 83R, the ring is always wet, the ground strap is just a tad lighter than black, but it runs pretty damn good!! (the mods are in the sig) just for the bigbore they call for a 135mj but i'm at 138, and the BRV says to drop 2-4 sizes plus i have the 86 carb and K&N....am i going to end up around 120 or 115 lol? mean while i have heared of some ppl on here running like 300 for a main!!! (or is that mikuni talk?) anyways i have ordered 6 smaller in sequence but they can't get 2 of them, so i'm going to haveto just work with what i get!!
thanks for all the help!
this is by far one of my fav threads!

Frankencelery
03-31-2007, 01:43 AM
I have a 200s with a new aftermarket carb that I've always had trouble with. The bike must be choked for about 5 minutes before it will idle, and then the choke can be turned off. However, if you punch the throttle, it bogs big time. It doesn't do that if you leave the choke on. I have no trouble as long as I'm easy on the throttle, and the machine runs fine at WOT. I posted on this issue some months ago, and I never reported back in to say what happened.

At the time I played with the pilot screw and couldn't find anything to improve the situation. Then I moved the needle clip in both directions with no improvement. So I gave up, thinking I would just have to replace the carb. This week I had another idea, so I bought a 200s carb kit and replaced the carb's 38 and 88 jets with the kit's 35 and 100 jets. I thought the smaller pilot jet was odd, but that's what came in the kit, so I tried it. It required quite a bit of adjusting of the pilot screw to get it idling correctly again, and now it starts and runs fine, but it still bogs when I punch the throttle.

Does anyone have any ideas of where to go next on this? I'm stumped.

Dammit!
03-31-2007, 01:53 AM
I usually adjust the air screw for best off idle throttle response. If that doesn't get rid of it, richen the needle clip one slot (at a time) and see if it improves.

Keep in mind, it's impossible to say for sure without hearing exactly what it's doing and knowing exactly where in the throttle it's bogging and how hard you're punching it. Even my 250R will bog a little off idle if you stab the throttle as hard as you can while it's idling.

Frankencelery
03-31-2007, 02:08 AM
No, it's my only trike that does this. If I'm sitting at an idle and I push the throttle just hard enough to take off fast, it bogs. I have to let off or it will stall. However, if I'm at half throttle already, I don't have the problem. My buddy's 185 doesn't do this, nor does the 200x or the 250SX.

Tomorrow I'll go back to the needle clip and adjust it again with the bigger jets installed. i haven't tried that yet.

Dammit!
03-31-2007, 02:17 AM
Sounds like the needle needs to be richer to me. Good luck with it. Let us know what happens.

Frankencelery
03-31-2007, 09:30 PM
Ok, Dammit......that sounds odd when I read it out loud. Anyway Dammit, I followed your suggestions, and moved the needle up one notch at a time. I ended up with the clip in the bottom slot and it's quite a bit better. It's still not quite like I think it should be, but at least now I can *almost* pull a wheelie off the line.

I've got the original carb rebuilt as well, and I might just throw that back in and see what happens. I did compare the two, and they are pretty much identical, so I can't see what the problem might be. I wonder if there's something engine related and not carburetor related?

NOS_350X
05-21-2007, 09:03 PM
Here is a little trick to find out if your lean or rich. It dosent always work but does quite often. If your bike is sputtering and not running properly Turn the choke on 1/2 way if you can. See if that clears it up. If it does you know that in the rpm range your having the issue with you need to richen up your mixture. IF its a new 4 stroke fcr carb You can pull the hotstart that will lean out the mixture showing you if you need to go richer or leaner.

Yamada
05-23-2007, 08:30 AM
Question. I finally repair the major leaks on my ytm-200 exhaust and now at idle the bike seems to run at lower rpm. It is also more difficult to start ( 2 pulls, 1 before with an very leaky exhaust. other than that, tthe bike run very well, i m able to wheelie the 3 first gear ( with a ytm-225 final drive). Should I check the pilot jet?

Dammit!
05-31-2007, 03:01 PM
You will rarely ever have to change the pilot jet (unless you ride at a very high elevation). Just make sure it's good and clean and the stock size. You can fine tune that circuit with the pilot/air screw.

CoeShow
06-13-2007, 07:43 PM
Frankencelery,

try putting the 38 pilot back in. Make sure it doesn't have some minor obstruction while its out. You may even want to purchase and install a 40.

Your issues sound to me to be pilot jet related.

Good luck and ride safely.

tapper190
06-17-2007, 06:24 AM
Hi, I've done a few engine mods to my '84 200x, and was wondering how many jet sizes up I should start at? The things I've done is 1) installed a wisco piston (first bore over) 2) I believe the head was ported before I got the trike. The intake has been cleaned out. installed a new stock cam and valves. 3) uni air filter 4) cobra pipe and header. Thanks
Tapper

dizasterzrfun69
06-27-2007, 02:20 PM
I got an 85 R with a PT high rev pipe and boyesen rad valve. When i try to run it it will bog out at bottom end and eventually die. I pulled the plug and its really dark with lots of carbon on it. Its a br8es plug and my main is a 145. My instinct would tell me to drop the main down like 2 sizes and try it there but its bogging on bottom end and not top end so what should i adjust?


I just checked the slow and the needle. The slow jet is a 52 like the book calls for and the needle is dropped all the way down.

RedRider_AK
06-27-2007, 02:44 PM
play with your air screw and/or pilot jet. Also play with your needle.

Dammit!
06-27-2007, 02:52 PM
I got an 85 R with a PT high rev pipe and boyesen rad valve. When i try to run it it will bog out at bottom end and eventually die. I pulled the plug and its really dark with lots of carbon on it. Its a br8es plug and my main is a 145. My instinct would tell me to drop the main down like 2 sizes and try it there but its bogging on bottom end and not top end so what should i adjust?


I just checked the slow and the needle. The slow jet is a 52 like the book calls for and the needle is dropped all the way down.

Are you running the stock round slide 85 carb? Where exactly in the throttle is it bogging? Will it idle? If it idles you don't need to mess with the pilot. My gut says your needle is too lean (can't trust plug readings in that range in my experience). I'd put the clip in the middle and see what it does.

dizasterzrfun69
06-27-2007, 02:58 PM
Are you running the stock round slide 85 carb? Where exactly in the throttle is it bogging? Will it idle? If it idles you don't need to mess with the pilot. My gut says your needle is too lean (can't trust plug readings in that range in my experience). I'd put the clip in the middle and see what it does.


well i JUST got this project finished AT trikefest, it ran good for the first day or so, then all the sudden one day it started bogging on the bottom end when id press the throttle. Now it wont even hardly start, when it does though it wont hardly idle and when i give it any throttle at all it just bogs out and dies. I Am going to put a new plug in it and see what that does. The plug in it was real dark though so thats why i think the carb itself needs something adjusted. Its the stock round slide carb.

Dammit!
06-27-2007, 03:08 PM
You have the needle on the top clip right? That's the leanest setting. What you're describing sounds like it's not getting enough gas.

Do you run it with the airbox lid on or off? If you run with it off, put it back on and see if there's any improvement at all. If there is the slightest improvement, your needle is too lean.

I have doubts that a 145 is rich enough with that pipe and rad valve as well but you won't be able to dial the main in until you at least get the needle good enough that it can run. You should dial in the main first, then the needle, then the pilot and/or air screw and idle.

dizasterzrfun69
06-27-2007, 03:21 PM
You have the needle on the top clip right? That's the leanest setting. What you're describing sounds like it's not getting enough gas.

Do you run it with the airbox lid on or off? If you run with it off, put it back on and see if there's any improvement at all. If there is the slightest improvement, your needle is too lean.

I have doubts that a 145 is rich enough with that pipe and rad valve as well but you won't be able to dial the main in until you at least get the needle good enough that it can run. You should dial in the main first, then the needle, then the pilot and/or air screw and idle.


yes the clip is all the way on the top of the needle. The manual calls for it to be on the 2nd clip. The carb right now is how it was when i got it. I have the lid on and i have a K&N filter in the box. Do you think it'd be wise to just put the clip in the 2nd position like the manual calls for, put the stock main in it and go from there?

wouldnt it be too rich though if it bogs and my plug is black? You said you think its not rich enough.. :confused:

Dammit!
06-27-2007, 03:30 PM
If it's bogging like the way they do when you run out of gas, it's far too lean. Too rich usually causes them to sputter like there's more gas going into the combustion chamber than it can burn effectively.

Changing the pipe, reeds and air filter drastically changes the potential flow through the motor. Right now you're flowing way more air than fuel. You have to increase the fuel flow to compensate.

Put it this way, you're way more likely to damage the motor by running it too lean than by running it too rich. When I jet a motor I intentionally set everything WAY too rich and work my way backwards. It's possible to have a motor running lean enough to damage it and not even know by the way it's running. That's how people burn holes in pistons.

dizasterzrfun69
07-02-2007, 05:37 PM
Rich: A "rich" condition is what occurs when you have too much fuel in your fuel/air mixture. Symptoms of a rich condition can be a rough running engine (sputtering), a black spark plug, a wet plug or excessive plug fouling.


If the engine does not quickly return to idle after a good rev, it's too lean and needs a bigger pilot jet. If there's bogging when taking off or reving from idle, it's too rich. These problems can often be tuned out with the air screw.



So which is it? I have a wet plug and it wont idle down. I turned the air screw all the way in and it didnt do anything. I put the needle clip in the middle groove and it runs good now. It wont idle down though and i have a wet plug. I think its getting too much gas. It has the stock 52 slow in it and a 145 main like i stated before. After one of my "rev's" I pulled the slide out of the carb and there was like smoke coming out of the carb. Im guessing this was vaporized gas and its getting too much fuel. :wondering

Dammit!
07-02-2007, 06:03 PM
Turning the air screw in cuts off air flow and makes it richer. What does it do when you turn it out? Does the idle screw or a combination of the idle and air screw have any effect at all? What does it do with the airbox lid on/off?

Unfortunately there's no way around the most unpleasant part of dialing in a bike. Trial and error. Sometimes they do they opposite of what you think they should but just keep trying until it starts improving. If going richer then leaner have no effect, there's a good chance you have another problem (electrical, crank seal, intake leak, etc). Sounds like you're getting close though.

Remember that they changed to a 42 pilot in 86. Different carb but that's still a big drop.

3WheelsOn2
07-09-2007, 09:16 PM
A couple days ago I read this thread trying to figure out why my 200x was sputtering at about 1/4-1/2 throttle. I then raised the needle a notch (to the bottem notch) and it got a little better, So then I put a tiny washer under the little snap ring, and now it has amazing top end and mid range (from about 1/4 throttle and up) on a gravel road going about 25 it breaks the tires loose in 3rd... (alot of that is because my tires are almost worn off) also
The throttle responce is amazing. And it idles great

But if I hold it between a idle and 1/4 throttle it almost dies, some times it does. and it misses...

any ideas?

Dammit!
07-17-2007, 01:04 AM
You say the needle clip is on the bottom notch now? Where was it before?

3WheelsOn2
07-17-2007, 12:30 PM
one before the bottem. if this was the needle then its on this one

|||||----------
^

Dammit!
07-17-2007, 06:22 PM
I would call that the top ring, not the bottom one. It gets confusing because lowering the clip actually raises the needle position. I like your illustration though.

The reason it's wanting to die at low throttle is because it's starving for gas most likely. That is the leanest needle setting. As soon as you start to open up the throttle, a rush of air comes in through the carb but not enough gas is mixed with it because the needle is still too far down into the main jet. Move the clip down a couple notches to raise the needle out of the main jet earlier in the throttle movement.

With what you're describing, I'd start with the clip in the middle.

3WheelsOn2
07-17-2007, 08:12 PM
Sorry but I didn't notice that it moved my arrow back when I posted it, What I ment to post was this

|||||-----------
---^

Now that I have it on the

|||||-----------
----^

could getting gas to early make it miss real bad?

Dammit!
07-17-2007, 08:31 PM
Too much gas will make it pop and sputter. I'd still try it in the middle.

3WheelsOn2
07-18-2007, 12:59 PM
ok, I'll put it on the middle and see how it runs. Thx for the advise.

burnoutboy
08-08-2007, 06:26 PM
I am having some issues with my rm250. When give it 1/3 throttle, black smoke comes out of the exhaust. When I get into the powerband the motor feels very "zingy" but is not producing any power...any idea what is wrong?

stoney420
09-12-2007, 03:05 AM
excellent read up here, thx alot dammit!

one question tho..



1. Use a new plug, clean air filter and have your bike, trike or quad warmed up to the proper operating temperature.
2. Make a WOT pass through at least 5th gear. What's WOT? Go back and re-read Dammit's first post.
3. Doing all four at the same time, hit the kill switch, let off the throttle, pull in the clutch and roll to a stop. (Rolling out anytime without pulling in the clutch could cause a seizure as the piston will continue at high RPM through it's stroke without pre-mix lubrication and it'll overheat and seize in a hurry. Running out of gas will do the same thing).
4. Pull the plug and read it. The porcelain insulator should be a nice cocoa brown, not on or near the tip, but down inside the plug. If it's still white or light in color you're running too lean and if it's black and or oily your running too rich. Re-jet, go back to step one and start over.

how would i do a "plug chop" for my main jet on my ytm200 that dont have a clutch so i cant shut it off and coast to a stop?

Dammit!
09-12-2007, 10:50 AM
Just let off the gas and kill the motor. Automatics will coast in gear.

stoney420
09-12-2007, 11:44 PM
oh ok thanx, i figured it would lock up when u hit the kill switch cause u cant push it when its in gear..

Dammit!
09-13-2007, 12:38 AM
I'm not an auto expert but the couple I've had would roll in gear. Try it going slow first I guess.

rally4x4racer
09-24-2007, 03:20 AM
i chop the autos in nuetral - seems to work fine.

also - I wanted to add some more info on the plug reading. http://www.4secondsflat.com/Spark_plug_reading.html it is not for dirt, but helpful no doubt

frankencelery - did you get that fixed? sounds like a needle diameter prob. look at the keihin page posted earlier

good work, dammit!

Frankencelery
09-24-2007, 10:03 AM
No, I never did. My 200s hasn't been run for awhile, and I've been trying to replace a tire that doesn't hold air, so I haven't gotten back to it. I think I'll try putting that 38 pilot jet back in when I get around to it.

The Goat
10-14-2007, 01:31 AM
1985 200x bored two sizes over, no air box lid, cobra exhaust. i'm prolly 100 feet below sea level or so, what should my carb settings be?

i know all trikes are different, but if i could get just a general idea.

main jet, pilot jet, air/fuel and needle position?

big schott
10-21-2007, 11:32 PM
I am working on a 1984 Big Red for a friend. The carb needed cleaning and I went through everything like I have 10 or 15 times before (on other machines).
The 200 starts everytime on the first pull and does not need the choke (odd for Minnesota in Oct). I took it for a ride this afternoon and found it to sputter at 1/4 and 1/2 throttle and it did not seem to run good at top end (Air Fuel needle at 1 1/2). I set the air/fuel at 3/4 and it ran better. But when I turned the needel in all the way it runs good. I know that you should not run anything with the needle in all the way so that is why I have the Q?.

What do I need to do?

big schott
10-22-2007, 10:33 PM
I never thought about the air filter. I'll put on a new one, and I was thinking about the resetting of the needel.
I'll do this this week and let you know what I find.

THANKS!!

harley9399@veri
11-24-2007, 02:34 PM
need a carb for a ATC Big Red 1984 model 200es this machine set for 10years keeps filing plugs?\Thanks Mitch

Danold
01-11-2008, 06:06 PM
so I just got my 85 x done and im stoaked. The only problem i am having is it not running past 1/4 throttle and just bogs and sputters. It also will not idle.

However, when I put the chocke on it revs all the way out and revs quik and idles high.

I havent really messed with it because of not knowing where to start. But mabye one of you guys could help me out?

NOS_350X
01-11-2008, 06:47 PM
That would meen your running to lean. (choke richens it up) Pick up a larger main jet and move your needle clip down (raising the needle)

Danold
01-11-2008, 08:48 PM
ok ill give it a try. I was thinking it was runnig rich becuase when it was missing it was plowing greenish black smoke. It just looked greenish :crazy: mabye color blind or somthing. Thanx for the help.

CoeShow
02-23-2008, 03:45 PM
Usually if the engine seems to run better WITH the choke, it indicates that the pilot jet is plugged up or way too small, not the main jet. This does not mean that you may also have issues with the proper main jet size.

Avoid making numerous changes at once. Change one component at a time. This will aid in figuring out which circuit is causing the problem/s.

Good luck and ride safely

Danold
02-27-2008, 01:06 PM
got it fixed. The choke was messed up and wouldnt stay open. Also the main was bent from over tightening.

BELGIUM KXT250
03-04-2008, 06:09 PM
"When adjusting the air screw, tightening the screw is richer and loosening it is leaner. This is because tightening the screw allows less air to pass (resulting in more fuel in the mixture which = richer), loosening it lets more air through."

I don't really understand that because I checked at my carb and by tightening the air screw it raises up the throttle valve so I was thinking that it allows to let more air to pass and so it's leaner... could you explain where I am wrong ?

Billy Golightly
03-04-2008, 07:13 PM
What your turning is more then likely an idle adjuster and not the air screw :)

NOS_350X
03-04-2008, 08:40 PM
Also rember, what are you changeing, most the 4 stroke carbs dont control the air, it controls the fuel, so tighting it up will make it leaner. The 2 stroke carbs are controled by the air. Also some of the 2 stroke carbs you can turn the choke to adjust the idle. screw it in would be lean out would be rich.

BELGIUM KXT250
03-05-2008, 04:42 AM
Hi,

Yes my carb is for a 2stroke engine (kxt tecate 86) and I was confused between the air screw and idle adjustment. You are right I must have adjusted the idle screw and not the air screw because this idle is the only screw located on the outside of the carb.

zoomerman
03-13-2008, 03:58 PM
I recently put a 86 carb, power reeds, and dg national pipe and type two silencer on my bike( 83 250r) but haven't started it because of jetting issues. Around what size main jet should i start with? the stock main for the 86 carb was 142 and pilot 50?i was told well it has a 52 pilot jet in it and a 125 for a main jet. The 83 carb comes with a 50 pilot and a 130 main. I would like to start jetting rich like Dammit stated, but i don't really have any idea. Should i buy a jet kit and start with a 138 or should i start bigger/smaller? any input would be helpful.

Thanks,

Evan

Dammit!
03-13-2008, 07:49 PM
I'd start with the stock jetting for the 86 R carb. If I remember right it's either 145/42 or 142/45. Can't remember off the top of my head which one of those is right. When in doubt though, go big. Less risk of damage.

Billy Golightly
04-28-2008, 09:57 PM
Dammit, I made this little guide thing for a plug a member posted in another thread, it might be a nice addition to the first post.

http://3wheelerworldforums.com/attachment.php?attachmentid=63995&stc=1&d=1209435037

Edit: Fixed watermark overlap.

dizasterzrfun69
04-28-2008, 10:01 PM
Dammit, I made this little guide thing for a plug a member posted in another thread, it might be a nice addition to the first post.

http://3wheelerworldforums.com/attachment.php?attachmentid=63994&d=1209434047

pretty cool billy, except the watermark on the bottom right.

Just-Tri-It
05-21-2008, 10:01 PM
I have a 1983 or 84 YTM 175. I premix the fuel as the oil tank was previously removed. I noticed that the vent tube which come out of the back bottom of the carb bowl is not vented to the crankcase cover next to the right rear wheel but hangs loose. When I hooked it up it filled the tube with gas and I had to take out the 3 screws to drain the casing. Why did it fill up with gas and is it important to have it hooked up there? :confused: Could I hook it up elsewhere. One gentleman said he thought it effected the timing if it was unhooked. I know it doesn't need to be filling with gas but don't know its original purpose.
Thanks for any imput.
sheeptender

Dammit!
05-22-2008, 12:17 AM
I have a 1983 or 84 YTM 175. I premix the fuel as the oil tank was previously removed. I noticed that the vent tube which come out of the back bottom of the carb bowl is not vented to the crankcase cover next to the right rear wheel but hangs loose. When I hooked it up it filled the tube with gas and I had to take out the 3 screws to drain the casing. Why did it fill up with gas and is it important to have it hooked up there? :confused: Could I hook it up elsewhere. One gentleman said he thought it effected the timing if it was unhooked. I know it doesn't need to be filling with gas but don't know its original purpose.
Thanks for any imput.
sheeptender

You'd have better luck posting this question in the main area. This thread is specific to jetting which is not part of your problem.

Tecate250
05-23-2008, 03:35 PM
So the ground strap is where to look if you suspect ignition problems, The color on the porcelin inside the plud tells you rich/lean "gas and air" ? What would running a b7es plug in a b8es engine do? I know it is a hotter plug.

Kintore
05-25-2008, 11:55 AM
Hey guys,

265 R PV motor, all mods in my sig

Runs fine first 3 gears then starts cuttin out the last 3.

Cleans out perfect but has a lil hesitation when you punch it after its been sitting a little bit.

Lean out my needle?

Thanks alot

DeePa
05-25-2008, 12:00 PM
Canadaman, i have no idea for you. IS it cutting out lean, or is it rich? What you have in there for jets? The more load on the motor, the more fuel it need...i would think?


As for a jetting question...Does the needle effect the wide open throttle? Like if you have the needle clip to the bottom, making it rich as possible, will the trike run the same wide open as when the needle clip was all the way at the top, makign it as lean as possible? Or does the needle just effect from low to mid rpms?

Thanks

Kintore
05-26-2008, 01:33 AM
Im going to drop the needle tomorrow and see,

wheres Doug when you need him!

Kintore
05-26-2008, 10:33 PM
Leaned it out 1 clip and it did the same thing, going to go another clip up tomorrow and see!
Damn thing

Dammit!
05-27-2008, 02:23 AM
Sorry I was out riding this weekend.

If you're saying it runs and revs out fine in the first three gears I'd be suspicious of the problem being something else. Electrical or maybe a crank seal. You're not being real clear though. Start with the main jet (see how it runs in all six gears wide open throttle). Get that running clean, then worry about the needle clip, then the pilot/air screw. If you can't get it cleared up with jetting, start testing electrical components. If you still don't have any luck it could be the left crank seal sucking some air.

Just-Tri-It
05-30-2008, 11:23 PM
I have a 85 Tri-z. It came with aftermarket pipes and performance piston and head and standard foam air filter. It has a 500 main jet and idles and revs pretty good. When I take off she goes fairly good but as I speed up and accelerate half way to 3/4, its starts sputtering real bad. I go into 2nd and easy accel. its good but as I get on it and it gets close to changing to third it sputters bad again. The needle is in middle position and air screw out about 3 turns. I have adjusted the screw some back and forth but it still doesnt take the sputtering out. Actually it makes it worse sometimes.
It had a 450 jet and at idle would sputtered hard when rev it. Couldn't ride at all. And no adjustment on screw or needle clip helped except worsened it.
The 500 made it idle a lots better but still if if take off and get on it good it will sputter bad.
Will changing the clip up or down help ar do I need to change to a different jet?
Are spark enhancer any help?

Kintore
06-01-2008, 05:31 PM
Got it guys

178 main, and all the way lean needle clip, Runs like a raped ape now!

oscarmayer
07-01-2008, 10:14 PM
if it's ok, i would liek to add 1 thing.
Learn to read your plugs. that is the single most important thing you can do. it will help you determine where you are int he tune and let you know if you need to ho bigger or smaller on jet sizes or even if your needle is in the wrong position.

but that part only comes in handy once you have learned how to jet and needle the carb.

oscarmayer
07-01-2008, 10:19 PM
I have a 85 Tri-z. It came with aftermarket pipes and performance piston and head and standard foam air filter. It has a 500 main jet and idles and revs pretty good. When I take off she goes fairly good but as I speed up and accelerate half way to 3/4, its starts sputtering real bad. I go into 2nd and easy accel. its good but as I get on it and it gets close to changing to third it sputters bad again. The needle is in middle position and air screw out about 3 turns. I have adjusted the screw some back and forth but it still doesnt take the sputtering out. Actually it makes it worse sometimes.
It had a 450 jet and at idle would sputtered hard when rev it. Couldn't ride at all. And no adjustment on screw or needle clip helped except worsened it.
The 500 made it idle a lots better but still if if take off and get on it good it will sputter bad.
Will changing the clip up or down help ar do I need to change to a different jet?
Are spark enhancer any help?

still sounds like it's breakign up at the top end. have you checked your plug gap or even change the plug?
you still may beed to change the jet to a bigger jet. what doe the plug look like ( use a new plug to test and check)

you can change the a/c on the idle and lower end by changing the needle clip. the lower the clip the richer it runs. the closer to the top edge the leaner it runs. so if your at the bottom, you may want to move it to the middle and then chagne jetting sizes to like a 525 jet (or something clsoe to that). once you get the top end settled down, then it's easier to set the idel area. the top end area is what will most certianly damage the bike motor, not the idle area.
also is this a 2 or 4 stroker? i am not that fimular withthe Z bikes. (i know tuning, but 2 and 4 have slight tweaks to help)
if it's a 2, make sure your running 35:1-40:1 fuel to oil.

Hoosier_Daddy
07-23-2008, 01:19 AM
I've seen a few conflicting opinions in this thread. (maybe it was typos) So let me get it straight. If it bogs in the bottom end then pulls out of it when you get on the gas, it's lean right?

tecat-z
07-23-2008, 01:35 AM
A bog right off of idle, or when the throttle is stabbed at low rpm's is almost always a lean condition. Raise needle one clip at a time. Remember, to raise the needle, lower the clip.

Dammit!
07-23-2008, 10:14 AM
You have to adjust it too far in each diretion to hear the difference. It's really hard to describe the way these things sound in text. Being way too rich can make it stumble off idle. Being too lean it will bog and sound like it does when you forget to turn the gas on. I edited the original post a little bit to make it less confusing.

The name of the game is experimentation. Don't be afraid to mess with these things. Going too lean or too rich just long enough to hear it won't hurt anything.

Hoosier_Daddy
07-23-2008, 03:19 PM
Ok, thanks guys.

jims72
10-14-2008, 03:13 AM
I just did the top end on my 200x and noticed when it is first started it smokes a bit then once warmed up stops is this a sign of being too rich?I know briggs motors will smoke if too rich.

Just-Tri-It
10-25-2008, 03:40 PM
I have a 85 Tri-z with after market pipe and oem muffler. I believe a Weisco piston is in it but not for sure as it came this way. It runs decent if you play with the throttle but taking off fast and then changing gears and stabbing it will cause major sputtering through all gears unless you ease off the throttle, and it clears up alot. It had a 500 main jet and I had a spare 450 so I placed it in it. It revs and idle better with the 450 but the wot and running thru gears with 1/2 or 3/4 to full makes its sputter badly. I have the clip all the way up allowing it to go down further in the carb and the idle screw is around 1/2 trun out for best performance . I thought the 450 would have made it bog at wot but basically its the same thing.
Any thoughts would be helpful.
Thanks

Brad200X
11-02-2008, 12:59 PM
Somebody on this thread said this already I think: don't always assume that your
jetting is the problem. My bro messed with his carb for weeks to no avail. Turned
out that he bought two brand new plugs and they were both bad!

Just-Tri-It
11-02-2008, 08:47 PM
Somebody on this thread said this already I think: don't always assume that your
jetting is the problem. My bro messed with his carb for weeks to no avail. Turned
out that he bought two brand new plugs and they were both bad!

This is true. I went through 8 different jets before changing the coil and finding out that it was breaking down esp. after it warmed up. It has a 500 jet in it with after market piping and bored 40 over. Yet it kept acting like it was getting to much fuel. I worked my way down to a 400 to no avail. On a hunch and desperation I started looking at the electrical and changed the coil, went back to the 500 jet and now I have to grip the sides with my legs like I'm holding on to a bull to stay on the thang. If I'm not careful it will give a new meaning to bring a tree hugger. I took it for a test run and came back, got off and stayed off for a while til my nerves calmed down... and I own 3 of em!
But that article on checking the electrical came to mind and whaala...ZZZZZZZZZZZZZZZZZ's too dang fast.

So go on and

Just
TRI- IT!!!!

Autophysn
12-03-2008, 03:11 AM
Hey Dammit, just wanted to thank you for this thread bro, It has helped me tremendously

3Razors
12-07-2008, 12:55 PM
Here is a link for 2 stroke plug chops:

http://www.dfn.com/benkaren/plugchop.html

yooper1
01-06-2009, 12:38 AM
i have a 84 honda big red 200ES i had new rings and crank seals put in and ever since got it back going fouls plugs left and right. i cleaning the carb and i mean a good cleaning. i put the pilot screw back to 1 7/8 turns out and tried it still fouled plug jst not as fast so i tried moving the jet needle clip down one notch and fouled it so i moved it up on instead and fould seems like fouls faster after moving needle clip i am at a stand still because i i dont understand it because before i had the repairs done it ran like a top never had no probs and only had to change plugs on it maybe twice in many years if any one has any info for me that can help me i would greatly appreciate it wanna get the ol girl running again had to see her at the junk yard thanks :wondering

Dirtcrasher
01-23-2009, 12:43 PM
Suddco has a book for tuning the VM and TM carbs. It took awhile, but I did find something similar for free here:

http://www.mikuni.com/pdf/vmmanual.pdf

Hopefully it will help me out a bit, headed back out in about an hour or so :D

daniel_250r
02-09-2009, 04:35 PM
i have a carb question my 200s will never idle right i adjust the idle screw it idles at a nice pace, give it some gas and it takes a really long time to go back down, week later i start it up and its idleing really fast and i didnt use the choke or anthing

Dammit!
02-09-2009, 07:02 PM
Have you tried adjusting the air screw? I'd richen it up a bit and see how it goes. Not sure which direction is richer on those carbs though.

Mosh
02-09-2009, 07:09 PM
My 70 and 90 carbs are stock and were doing this..

Over time, the idle speed screw causes the slide to get rough.Then the slide will not always return to idle, or snap past the burr in the slide, and idle too low.

Remove the slide, and you will see a ramp section where the idle screw contacts the slide.You will see a divet, or rough spot in the slide ramp,from the screw contacting it for so many years.
Take a fine tooth file,and file that smooth again..Then re-assemble and adjust..
Just a simple tip before you go changing jets..

daniel_250r
02-09-2009, 10:38 PM
alright thanks, a part of me also thinks a clamp is loose or hole is in a boot causing an air leak but we will see

ThinktwiceZ71
02-12-2009, 09:23 AM
hey guys , i just rebuilt my 200s engine , while doing it i rebuilt my carb also with a moose carb kit from dennis kirk , it had a new needle , seat , pilot jet , air srew , main jet (plus the usual washers gaskets and orings). All were the size that was in it before the rebuild. here is the thing that confuses me , before the rebuilt it was running rich , black carbon soot on the plug when checking it , but i had peace of mind knowing i would never be lean. now after rebuild and setting the carb back to factory specs i take it for a little ride last night and it rides awesome , but the plug is damn near white. I called the honda dealership and they said to lower the clip to position 4 (3rd is stock) ....i did that and i turned the air screw in a little (add a little more fuel) and the plug is a light grey now. do i need to go to a 105 main jet ? (100 is stock) along with a 35 pilot jet is what is in it.

i have a cob jobbed air box lid on it that does not seal , and i have a aftermaket pipe that leaks some too......i know i should get it fixed but i am going to run it like this for now.

i just don't get how i was really rich with this setup before , and now after rebuilding with the same size jets and stuff , i am way lean.

anyone ?

benjoefoe
03-02-2009, 08:57 PM
I bought a brand new factory replacement carb for my 1985 Honda 185S, the first day I put it on it ran good, 2nd day it was sputtering a little so I tryed adjusting the idle and pilo screw but only screwd up the settings, now I can't get it to start. Is there any standard setting these screws are set at in the factory? Anyone maybe have pics or advice I can go by?
Thanks!

ledgettc
06-25-2009, 04:53 PM
Thanks for the great info...
I have an 86 200E yamaha that had been dying intermittently. I can run for 4-5 days w/o any problems, then boom be out on a run and it will just die. Once I get it started it will idle but once I go to take off it dies at less than a 1/4 throttle.

I thought I would pull the float bowl and make sure that the fuel is not contaminated, but that is about the depth of my knowledge on carbs.
Do you have any thoughts?

Thanks,
Chris

mohadib
08-03-2009, 05:00 PM
Can you do plug chops in netural setting still? Sorry if this is a goofy question. Thanks.

NOS_350X
08-03-2009, 06:29 PM
No, must have a load on the enigne.

jaredj
10-02-2009, 02:04 PM
i have 110 1980 atc that i just picked up. I changed the plug, air filter and installed a carb rebuild kit. The bike cranks on first pull and idles fine. If i ease into the throttle and then open it full it works fine, but if I go straight into wide open throttle it bogs out. Not sure if bog is the right word, but basically it wont do anything. When riding as i shift it does the same thing. any ideas? my only experience is with lectron carbs. any help.

Thanks,

scottp597
10-18-2009, 09:25 PM
The guide says bogging is a lean condition, but when adjusting the pilot circuit if it bogs off idle its rich??? I am confused by this

My machine bogs off idle, I believe it is too rich but I'm not sure what to adjust. Turning the screw out to like 5 turns clears it up I believe. So it must be rich, I'm thinking about raising the clip or getting a smaller pilot. Not sure

austinkay2k7
11-03-2009, 12:53 AM
Ok, very informational and helpful article, but i need more info. my 83 atc 185 will run well with the choke on, and will idle great with the choke off, but will not run at all above idle with the choke off. i dont know what to do.... thinking about buying a new carb....

MagicJames
11-03-2009, 10:53 AM
Ok, very informational and helpful article, but i need more info. my 83 atc 185 will run well with the choke on, and will idle great with the choke off, but will not run at all above idle with the choke off. i dont know what to do.... thinking about buying a new carb....

Is your carb clean? That would be the first step. Take your carb apart and take all the jets out and clean out your jets, or replace them.
Get a can of carb cleaner and clean out every little nook and cranny.
Re assemble the carb and if you're still having problems i would check your idle. jet, it might be too rich.

Just-Tri-It
03-30-2010, 02:35 PM
I have a stock 85 Z except for K&N air filter and DG silencer. She idles well but when you gun it or stab it to rev it up and let it rev back down while sitting still it doesn't have a clean crisp rev. If has the rapid misfire but not the bog. About like the rapid misfire you get when you 're doing a WOT in 4th or 5th gear. Just a fast misfire type sound. Like it really wants to get up and run but something is holding it back.
But it's when it's sitting still that I'm talking about for now. This is what I have done to no avail.
The manual calls for a 470 stock main jet which is what's in it. I have the chip on the 3rd slot. Air screw 2 turns out. I have changed the main jet from a 400 to a 500 in increments of ten and worked the air screw from one turn out to 8 turns out and it's the same on all the jets with no help in rev. for a clean rev.
I'm wondering if I'm dealing with the wrong jet for getting a clean rev when she's just sitting still. Maybe different jet is responsible for that area when she's just sitting and idling. I know it may be electrical.
I thought about changing the reeds to see if this would help. Thanks for any suggestions.

Also I can't find this thread front the new board menus. I had to use a saved link to get to it. Is it still listed under the Trikesylvania Forums or am I just over looking it?
Thanks

jk5blazer
04-03-2010, 11:26 AM
Alright, I know this post is kinda old but Im really needing some help. Is there a link someone has that shows stock jets? My 86' 250 sx is sputtering/bogging at WOT, the plug is black, and the air/fuel screw has no affect. I just bought a Shindy Carb re-build kit for the 86-87 250sx and put it toghter. The old jet that was in there was a 125 and the new one is a 130. I dont know of the pilot right now, have it writen down in garage but it idles pretty well. I put the 125 main back in because the bogg/ sputter got worse i think. It was noticable before now I cant ride it. Any advice? Should I go even further down in main jet size?

scottp597
04-03-2010, 06:59 PM
If it is sputtering at WOT and your plug is black then your main jet is too big. I would buy a clymer manual, search for an owners manual on this site, or see if someone can chime in on the stock recommended size for that machine.

After you change the main jet and your WOT feel is correct, you may need to then adjust your air screw and needle position to get the off idle throttle response dialed in.

scottp597
04-03-2010, 07:06 PM
http://www.oscarmayer.net/atc/manuals/honda/atc250sx_85-87_servicemanual.pdf

jk5blazer
04-03-2010, 07:34 PM
I just found out that it runs great 1/3 thur WOT if I have the air box lid off, just not from idle to 1/3. So I guess that sums up the fact that its running rich.

jk5blazer
04-04-2010, 09:37 PM
So the main jet stock is 130 and there is a 125 in it and its still running rich. Does that happen? How many different sizes should I get? It runs great if the air box lid is off, just idles real high. I was thinking 120 and 122. any other thoughts? I dont want to just throw money at this thing, well anymore then I need to that is! Thanks

Dammit!
04-06-2010, 01:09 PM
Just wanted to mention that this thread doesn't get checked often. If you have questions that you can't figure out from the info posted here, it would be best to start a thread in Trikesylvania to ask for help.

jk5blazer
04-06-2010, 01:13 PM
to be honest I have! I know i cant expect an instant responce but..... I will try again, thanks for the 411 though.

RIDE-RED 250r
06-15-2010, 09:34 PM
i will admit that i didnt take the time to read the entire 9 pages, but i noticed on the first post with definitions that piston wash was not included as a means of determining burn condtions. plug chops are good, but piston wash is better if you dont mind wasting a head gasket or 2. i would say, plug checks to get close, and piston wash check to verify and determine thumbs up, or thumbs down when you think you are dialed in. on a 2-stroke a good wash pattern will show about 1/8 of an inch of clean piston around the outer circumference of the top of the piston. and where each transfer port is, you should see clean or "washed" piston about the size of a thumbnail. if the entire top of the piston is black with no wash anywhere to be found you are lean. this occurs because the cumbustion chamber temps are so hot from being lean the the fuel coming in starts to burn immediately. when you have proper wash, (proper mixture/combustion chamber temps) the fuel comes in and keeps the top of the piston in the areas i mentioned clean. and abviously, too much wash indicates a rich condition. basically, if no wash occurs, it indicates things inside are getting hot enough to start to damage the piston, particularly on the exhaust side of the crown. hope this helps some, and that i didnt just repeat a previous post.

check out this link, i know its about sleds, but the same principle applies and i think this is a really good write up with pics on piston wash....
http://www.dootalk.com/forums/index.php?act=attach&type=post&id=115122

Dirtcrasher
06-15-2010, 10:20 PM
^ Great post!! :beer

Unfortunately most guys are lucky to get the jug on once, let alone twice!!

Hopefully starting rich and reading the plug will do the trick.........

Great advice to share though :beer

RIDE-RED 250r
06-22-2010, 08:07 PM
^ Great post!! :beer

Unfortunately most guys are lucky to get the jug on once, let alone twice!!

Hopefully starting rich and reading the plug will do the trick.........

Great advice to share though :beer


happy to help in any way i can....as to removing the jug, i think in most cases with the tank out of the way, you could get a good enough look at the piston crown by just removing the head and bringing her up to TDC. of course this may not be true of all machines with different engine/chassis layouts.....

hossola
07-11-2010, 08:40 PM
Hey bro thanks for all the great info! I know that these post are some years old but I hope that you are still around. I recently bought a bike that had been sitting. I cleaned out the carb real well and it started right up. The bike runs well but once I have top gear/ top speed it backfires and bogs out. It wont start for about 5 minutes. It doesnt seem to ever die like that when I am not gunning it. It also NEVER backfires at low speeds/ gears. Any ideas? I bought a carb gasket kit that is coming in a couple days. When i replace them I am going to make sure that the jets arent clogged and that they float is at the right level. Anything else I should check or alter when I have the carb apart?
Thanks much.
Rob from PHX

skypilot
08-18-2010, 12:54 PM
Hey guys, I'm running a stock (except for Cobra header and muffler) "85 Honda big red. I built a snorkel out of 1 1/2 pvc pipe and installed it like the one mondex is running here on the site. When i installed the snorkel, my trike ran terrible in anything above 1st gear, fine at low idle. When i get up to speed in say third or fourth gear, engine bogs down, and starts hiccuping back through the snorkel. Going down the road, their is air blowing out of the snorkel? But at idle it is sucking air, I can kill it by placing my hand over the snorkel inlet. Is this a jetting issue? Trike ran great in stock condition, except for backfiring when you let off the gas going down hill!?! Crazy I know! The stock air filter is a steel mesh type? I'm thinkin, no foam--it was this way when i bought it. So what's up? Is this related to the air filter or jet's in the carb. I live in east texas, and this is primarily a mud machine and trail cruiser. Thanks for any help from the trike docs!

RIDE-RED 250r
08-30-2010, 07:18 PM
sounds like the foam element is missing. the steel mesh is doing nothing to filter out small dust particles, its just there to support the outer foam element that catches all the harmful debris. get the foam outer filter on there...and its possible your snorkel is restricting airflow and you may be running too rich. do a plug chop at half and full throttle (if possible) and take plug reads...this will tell you alot. if the chops arent possible the way its running now, get it to the point its spitting and carrying on and bop the kill switch. then pull you plug and see what it looks like...my bet is that it will be black and wet.....meaning rich

85 250sx
10-25-2010, 11:20 PM
ok so i thought i had everyting dialed in and running good. it doesnt bogg out or spudder but i just noticed that if i run out of gas it starts to rev like crazy! first time it happend i thought it was gona blow up but luckly i hit the kill switch pretty fast. this is on a 2 stroke by the way. does this mean its running to lean?

Dammit!
10-26-2010, 01:11 AM
It only does it when you're running out of gas? When it runs out of gas, it is by definition running lean. REAL lean. lol

85 250sx
10-26-2010, 06:58 PM
yeah it only does it when i run out of gas. and well yeah at that time and moment its REALY lean since i have no more gas but should it rev like crazy like this on its own? i mean it sounds like im holding in the clutch and giving it gas wot. i dont think ive ever had this problem before on other bikes when i run out of gas on other machines they just kinda bog out and die.

Dammit!
10-26-2010, 11:20 PM
I never run mine out of gas so I couldn't tell you how normal it is. I just know it's possible. Maybe risk some "duh!" replies and ask in trikesylvania if nobody else responds in here.

toyota_guy83
11-09-2010, 04:33 PM
Ok guys, come and save my KLT 200 from my M1 Garand. I have spent alot of money and countless hours trying to get this thing to run properly, from swapping in a KLT 250 shift rod, new cam, rockers, valves, cleaned satan himself out of the carb, brand new oem spec spark plug, cleaned the fuel tank, replaced all the fuel lines, fuel pump and filter, cleaned the carb some more and still it bogs in what I gather is the needle jet circuit (1/4-2/3 throttle) I have tried every single clip position and screwed with the air screw for each one, the air filter is clean and airway not obstructed, intake boot is siliconed to the head and all hose clamps are tight. Tip in is great but if I try going past 1/4 throttle from idle it will stall out and die until I let off. Like it doesnt even fire. But if I rev it up a little into the mid range, it will rev fine at any throttle position. I'm losing my mind as images of FMJ .30-06 rounds pass through my mind. Can anyone help me please?

Dammit!
11-10-2010, 01:36 AM
I'd post all that same info in trikesylvania. It won't get seen by a whole lot of people in here. Keep bumping it once a day if you need too.

Xpress
11-10-2010, 01:58 AM
Good read. I pulled my T3's plug out to look over, and not quite sure if I'm running good. Feels like it's got plenty of low end and runs full throttle.

http://img176.imageshack.us/img176/3479/img4017j.jpg

Based off of what I've read, I think I'm just a tad rich??

FATALS1CKN355
12-17-2010, 09:51 PM
Hey guys! I know this is totally the wrong topic to be posting on , but I seriously need help ASAP. My 1984 200es Trike is bogging out at high acceleration , wondering if ANYONE KNOWS WHAT THE PROBLEM MIGHT BE. I've heard things about timing , but i'm not 100% sure. Thanks for reading , hopefully this doesn't get bumped or spammed because I'm in serious need of help! Thanks guys!

FATAL S1CKN355

TurboTacoma
12-18-2010, 05:17 PM
Hey guys! I know this is totally the wrong topic to be posting on , but I seriously need help ASAP. My 1984 200es Trike is bogging out at high acceleration , wondering if ANYONE KNOWS WHAT THE PROBLEM MIGHT BE. I've heard things about timing , but i'm not 100% sure. Thanks for reading , hopefully this doesn't get bumped or spammed because I'm in serious need of help! Thanks guys!

FATAL S1CKN355

Have you checked all the basics first. Clean air filter. Clean carb with correct stock settings (unless you have aftermarket add on's, then jetting needs to be done to make it right). Timing in correct spot. Is the mechanical advance working... springs in good shape and lubed up. New spark plug. etc. I am only trying to help. I just got my 2 atc 200's and had to go through them both like I wrote above, and then once I had a baseline. Then I modded them. Hope this helps! Make a check list to help eliminate the guessing what maybe wrong.

Nightmare
12-19-2010, 07:21 PM
What could cause alot of back firing on decel?

vanaman
02-23-2011, 11:01 AM
Ok so im getting my 84 200x rebuilt. During this time im getting a 12-1 piston put in, unfilter, and a performance exhaust. I also bought a "new" carb off ebay for it.

Where should i start out at? Should i just buy the next few sizes above stock and try them all out or are their kits that i should buy.

What should be stock on this trike?

Larry's Trikes
09-11-2011, 02:22 PM
I have been going through plugs every 3-4 hours and they are black and wet. Running rich I presume. They won't fire at all. I've dropped the needle valve one notch and no help. Do I actually need to reduce the maint jet seat size?:wondering

torque
11-25-2011, 11:23 PM
i have read this entire thread please for give me if i missed the answer.

what causes backfire on decel.

i got into a fight lol on the board and want to be set straight.

thanks

sbjones73
01-03-2012, 01:24 AM
ok people i have an issue with my newly installed 310 kit. a ittle information first.
85 250r esr 310 with a 38mm pj keihin carb. air box installed with cover removed and k&n filter in it. fmf fatty pipe and fmf silencer freshly repacked.

eddie sanders sugested running a 182 main and a 60 pilot. so i figured a little colder weather here in wisconsin right now, so i put in a 185 main and a 62 pilot.

this is what is happening. when i blipped the throttle, the rpm's hang up for like 2-3 seconds, then it idles fine. also, i have noticed that my idle adjustment (and choke on a pj carb) is like more than half way out (so half way choked)

so what i have done is played with my air screw. i am curently at 2 and a 1/4 out on my air screw (just checked) i have tried going in slightly to richen it up, but this did not really do anything.

so i need help here. i think i should should go one more up on my pilot jet, but what do you all think ?

note**** sorry for the double post. i put this in trikesylvania also *****

4x4van
03-06-2012, 11:31 PM
Just as a bit of added info; Many have asked whether the pilot (air) screw adjusts air or fuel. Every carb is different, but there is an easy way to determine which your carb's pilot screw handles. If the pilot screw is located on the air filter side of the carb (before the slide), then it adjusts the air (opening increases the air, closing decreases the air). If the pilot screw is located on the engine side of the carb (after the slide), then it adjusts fuel. :beer

thcowboy
04-05-2015, 09:35 PM
i have read this entire thread please for give me if i missed the answer.

what causes backfire on decel.

i got into a fight lol on the board and want to be set straight.

thanks


What could cause alot of back firing on decel?


If it is backfiring on deaccelleration it is very lean