Please help diagnose

[fxnteeth]

ok guys, I thought I was pretty good at setting up and jetting. I am in Louisiana, air box without lid, FMF fatty exhaust. engine is roughly a 280. I have had it a while and have never got it to run correctly on top end. Low end to mid it runs like a beast, top end sputters like its too rich. I have ranged the main jet from 150 to 200 and nothing really seems to change???? It is a 38mm Airstryker. After attempting to move the clip, the nut that holds the throttle cable is stripped so I may need to replace that, but is this not a good carb for the setup? Do I need another one. Plug looks good.
Please help. very frustrated
Jarrod

[fxnteeth]

OK, to replace the stripped nipple or cable holder is 46 bucks plus tax. Leaning towards another carb

[Addicted]

What model is it?

[just ben]

I think that main jet is way too small and running lean rather than rich. one of my tecates is .060 over (260) 34mm stock carb dg pipe and silencer K&N clamp on filter. i started at a 270 main and it ran the way you explain until I got up to a 290 I settled on a 300 and dropped the needle by one position. runs perfect and doesnt foul plugs. you didnt say what machine you are working on so obviously you will be in a different range of jets but a 200 is pretty small for a 38mm carb on a piped 280

[fxnteeth]

Sorry its an ATC 1985

[Slingblade]

^^Ben is quoting Mikuni numbers vs. your Kehin #'s, just trying to keep the confusion down. Sorry to hear your still having trouble with the R. Where did the Air Stryker come from? On it when you got it, Bought it , etc. Is this the only carb you've tried on it? I know you've tried about everything.

[just ben]

^^Ben is quoting Mikuni numbers vs. your Kehin #'s, just trying to keep the confusion down. Sorry to hear your still having trouble with the R. Where did the Air Stryker come from? On it when you got it, Bought it , etc. Is this the only carb you've tried on it? I know you've tried about everything.very true I didnt see it was a kehin I just saw 38mm. FYI a kehin 170 would be a mikuni 145 very small for that combo IMO

[fxnteeth]

YEs, the carb was on it when i bought it. I started with the mains because it is at WOT. I am on pump gas. Carb appears to be in good shape. If i want to try another carb, should I get the same kind or do you recommend other kinds

[RIDE-RED 250r]

Check your reeds as well.....

I am only at about 300 feet elevation. I have the same carb on my R. Im running a K@N filter, 1Dir Racing reeds and cage, FMF Fatty with FMF silencer, CR head gasket, and for what little diff it makes its bored .060. Mine settled on a 195 main jet with 110 octane. My plug is just a hair on the dark side of perfect. I have been having trouble with 1Dir's reed petals chipping at the ends and last time I changed them I was getting a high end burble, almost sounded rich. Went away with a fresh set of reed petals.

[fxnteeth]

Thank you. Will definately check the reeds and get some 110.

[RIDE-RED 250r]

You dont necessarily need 110 octane fuel. My engine is set up for higher compression with the CR head gasket. If yours is running the stock gasket you probably dont need any higher than 93, if even that much. I only run that because I have to with my current set-up.

[fxnteeth]

What compression are you running?

[Mosh]

I run a 38 mil airstryker on a .060 over, 85 R with heavy porting, Cr head gasket, and V force 3 reeds, FMF fatty with no lid, and a K&N.
172-175 main should be close for you. Actually a fuzz lean at that range, but they run better in the trails that way.

You said you have cable issues. Are you sure the slide is openeing all the way? Have you checked? Also I have seen about 10 250r's over the years bust up on the top end, due to rust on the flyhweel causing low pick up coil output at the stator. May want to yank the cover and check.

[fxnteeth]

thanks for responding Mosh. I have replaced the stator and the CDI, the flywheel looks good. Never thought about the slide. Ill check slide and reeds tonight. Are you running 110 due to compression?
thanks

[Mosh]

Yes I run straight 110, but could get away with 50-50 mix of 110 and 93 or straight 94.

[RIDE-RED 250r]

What compression are you running?

About 205 psi last time I checked it.


Mosh: its funny, we are running almost exactly the same add-ons except the reeds and Im on stock porting and I have to be jetted at 195 on the main. I am not liking the durability (or lack thereof) of 1Dir's reed petals. But dang they flow

[Greaser1]

I think the 38mm carb is a little too much for what you have from my experience. I would try running a 36mm PJ. Sounds like you have too much carb for that engine.

[fxnteeth]

Checked the reeds, they are brand spankin new. No probs there. Waiting on the cable holding nut to come in for the carb. To make sure the slide is opening. Greaser, why would you think the carb is too much for the motor when so many other people have a very similar setup with no probs. Any other possibilities.
thanks guys

[fxnteeth]

OK guys. Getting frustrated. The flywheel looks good. I replaced the Stator. and CDI box. I am getting good electricity. It runs great from idle to just before 75% throttle, then it feels like I hit a rev limiter. It wont pull through it. As mentioned above, the reeds look great, stock filter w/box, and no lid, fmf fatty. .060 over. 160ish on the main right now. HELP. Didnt get the compression tester or 110 today. I just got home and had a hell of day at the office.

[RIDE-RED 250r]

Dont waste your money on 110 oct before doing your compression test! I seriously doubt that is your issue. Any progress on the throttle cable? What is the color of your sparkplug? Need to figure out if this is a fuel mixture, compression issue, or mechanical issue. Sounds like you have eliminated ignition as a possible cause.

Put a new sparkplug in it after pre-warming the engine on an old plug. Fire it up, wind her up (in top gear) to full throttle. I realize it wont spool to WOT, but we need to get a look at your jetting at that throttle range. While holding WOT, kill the engine, holding WOT till it completely stops. (it goes without saying, but make sure you have adequate room to safely conduct this test, and wear your brain bucket!) Remove the new plug and tell us what color it is on the center electrode, if its soaking wet, or dry as a popcorn fart.

I have my doubts if its a compression issue since your trouble is at 3/4 throttle and higher, but you should check it just the same, just to be sure. Does it start easily and reliably?

It really sounds like a main jet issue to me at this point since your reeds are tip-top


I just went back and re-read the thread. You say you have had this trike for a while and it has had this problem since you first got it. Have you ever really truly disassembled and thoroughly cleaned the carb? Please dont take offense for my asking, Im just looking to find out what you have or have not done and your level of understanding of how to really clean a carb. I ask because I have had alot of people tell me they were cleaning their carb properly, and later found out they were just removing the bowl and spraying carb cleaner up into the carb body (which will get you nowhere). The 38mm Airstryker is a great carb and I was told by Tom (ESR Tech) that the carb is suited to run their 350 big bore. SO, that carb should be just fine on your engine. Its a very popular carb upgrade for these engines.


Good luck and let us know what you find out!

[fxnteeth]

Thank you so much for the thorough reply. She starts in usually one kick (if it doesnt break my foot). Bought the compression tester today. Didnt check it. Not sure how. At 75% throttle when the bike is off, it seems like the throttle spring gets in a bind, but it does open the slide all the way. Ive changed the main a million times. It sounds like i need to thoroughly clean the carb. I will then run an accurate plug chop and post pics. Any tips on thorough carb cleaning? And do i plug the compression tester in and kick it? How many times? Thx again

[just ben]

you got it. screw it in and kick until the guage stops rising. you will get different numbers on a cold engine than a warm one so take note of both

[fxnteeth]

thanks guys. Ill get it done probably tomorrow or Friday. Oh yea, Ride-Red I got my throttle cable nipple in and it is fixed.

[RIDE-RED 250r]

OK, good deal.

On your compression test, hold the throttle wide open. And like Ben said, kick it over till the guage stops rising. There is no set amount of times you have to kick it.

As to the carb cleaning, remove the carb from the engine and lay a clean rag down on the bench. Start my removing the carb float bowl. Inspect the float bowl for discoloration, debris or any other contaminants that dont belong there. Clean as necessary. Next, remove the main jet and jet tube. Once the main is out the jet tube should slide right out the top through the slide housing. This is the brass tube that the main jet butts up against to feed fuel up through the needle valve and then into the carb throat. Next, remove the float pivot shaft, float, and fuel metering needle. Remove pilot jet. The pilot jet will be in a small housing built in to the side of the main jet housing. It will look like a brass fitting recessed into the housing about 1/4 inch or so with a common flat screw head. Remove the idle airscrew from the outside of the carb near the slide housing. Before removing, turn it in and count how many turns it as set at and jot it down for future reference during re-assembly. The carb should be fully disassembled at this point.

Using laquer thinner, carb cleaner or any other good cleaning agent that doesnt harm aluminum clean averything you can get to. Pipe cleaners and an old toothbrush can be helpful to get all the fuel circuits cleaned out. If you have an air compressor, blow air through all the fuel circuits. Note: use caution forcing compressed air into main fuel inlet leading to the metering valve seat. Alot of times there is a small rubber insert in the seat that will fly out of there the second you put your air chuck to the fuel line fitting on the carb. Dont ask me how I know this! LOL! Basically what you want to do is make sure every little fuel and air circuit is clean and clear. You should be able to see right up through the main jet tube. If you see the slightest blockage it will give you problems. Its sounds more complicated than it really is. When you get the carb bowl off you will see what I mean.

Once you have your carb clean and the machine running well, be sure to use some fuel stabilizer if you store the machine without running it for more than a week or 2. If you live in an area where ethanol blended fuels cannot be avoided this is especially important. And be sure to use stabilizer that is for use in ethanol blended fuel such as Stabil Marine. I use it and it works great.

[fxnteeth]

Compression is 176.5 cold. Carb removed and disassembly will begin tomorrow. Thank you so much red. I really appreciate you taking the time to help me

[RIDE-RED 250r]

Any time, happy to help where I can. Your compression numbers seem normal for a stock setup, so 110 octane will not be necessary. I suspect you will find a partially blocked main jet circuit. Good luck.

[fxnteeth]

Couldnt get the brass tube out that the main butts up to. Here is what I have and it all looks quite clean. Any more tips or suggestions?13181513181613181713181813181913182013 1821

[RIDE-RED 250r]

Well, the carb does look clean inside from what I can see. If you look through the main jet tube is it clean and clear?

At this point Im unsure of what can be giving you the top end trouble. Looks like a dirty carb is not your problem, at least we can eliminate that as a possible cause.

Anyone think a faulty CDI could cause his topend issues??? Im stumped.....

Nice looking trike though, dont give up on her!

[just ben]

a faulty cdi is a possibility. from my experiance they work or they dont or are sensitive to vibration and cut out. one way to find out is isolate it from vibration such as pulling it off its mounts and zip tying or what ever with a foam pad underneath

[fxnteeth]

is there a feasible method of testing the CDI? Getting frustrated.

[fxnteeth]

BUMPity BUMP

[RIDE-RED 250r]

About the only method I know of is to replace it with a unit you know for sure works, say from another 250r that runs properly. Other than that, I dont know how to test a CDI.

[fxnteeth]

Thanks Red, I will try to find one this week.

[muthey]

here is another thought a friend of mine had an 85 liquid r years ago and his main issue with it was it didn't get enough fuel to the carb at wot, , from the size of fuel lines, it appears that you have adequate amount in the lines, how about float height settings are they correct?

[fxnteeth]

Update. Placed the new cdi and Holy $&@t. She runs like a scolded whore. Thank all of you for the replies and ideas. Man i love this site

[RIDE-RED 250r]

Glad to help, and glad you got her figured out!!! Happy Braappin!

[Mosh]

Update. Placed the new cdi and Holy $&@t. She runs like a scolded whore. Thank all of you for the replies and ideas. Man i love this site
Thanks for reporting back what the fix was.
All too often, people get help or have a problem, and it gets solved, but they never comeback to the thread to give the fix. Personally, I like to file these things away in my memory, just to refer back to if needed.
I feel if everyone did that on any help forum, it would be alot easier for the next guy to figure out his issue.

[fxnteeth]

agreed. I have read several open ended issues on this site, and never found out how they fixed. We would learn even more if we worked through from problem to diagnosis, to solving. Thanks again. I think it is a combination between the cdi and the badas& seat cover that mrs. mosh made that makes this thing so fast.
Jarrod