250r experts help

[bamatj]

I need some help figuring out what is wrong with my 250r. Here is the specs (the best I know): 1986 ATC250r, bored .030 over, FMF pipe, Boysen reeds i was told, with a small reed spacer (is this reed spacer factory?) 34 mm Keihin flat slide (also is a flatside carb stock?), Uni-filter with airbox lid on, and 185 psi compression. The current jetting i have now is 48 slow jet, 150 main, and a DGH needle. The jets and needle are brand new Keihin. My problem is I am way to rich. Idle to about 3/4 throttle is missing/bogging/sputtering/ just running like crap. When it finally clears up on the upper side it runs fine. But it wont rev hardly at all if you ease into the gas. I have tried different plugs and different gaps and i couldnt tell a differnce except i dont foul as many hot ones. But hopefully I wont run the hot ones anymore when i get it tuned in. I started out with the same size jets that I have now, just a different brand(not sure which brand). I have moved the needle all the way down and it runs slightly better all over except on top end, its a bit slower (probally to lean). But what gets me the most is its flooding so bad that you cannot adjust the idle or the mixture screw. From one extreme to the other it makes no differnce. Well the mixture screw will make it stumble at about 1/4 turn out, but after that its all the same. The idle adjustment can be screwed all the way up or down and it still wont idle. So help me if you can. One person told me the reeds might cause it to flood bad. But im new to 2 strokes so I dont. Is there any hope for this carb or should I just go ahead and punt it? Sorry for the long post.

[Dammit!]

Read the jetting sticky. Twice. ;)

[bamatj]

Ok maybe i was not clear enough. Im new to 2 strokes, but i can turn a wrench. Can somebody tell me why my carb would run so rich that i cant even adjust the idle or the air mixture screw? All the way in and out on the idle adjustment makes no difference. About the same way on the mixture screw. I have tried different slow jets, main jets, needles and needle postions. Hardly any diiference at all where i am having problems.Damnit, I have read plenty on jetting (and not just since ive been having problems). Im thankfull for any help but Im not looking for answers like check your float level. Ive worked on alot of quads but that was all 4 stroke. Im looking for an expert on 2 strokes. So far the only answers Ive got from other people is the slide could be wore out, or the reeds. I have checked the reeds. The are not broke/chipped/or cracked. Someone told me they could not have much if any of gap in them. But they didnt know how much of a gap. Ive got feeler gauges if somebody can tell me how much of a gap they should have. Also again, can anybody tell me if a reed spacer is stock on a 1986 250r. From what i can gather from searching most say they are not. But it sure lools like it is. Im not sure I can get the intake to airbox boot to fit if I remove it. Also can anybody tell me if the factory carb is flat slide? Thanks for any help.

[bamatj]

Ok i went out and took the reeds out. The top part of the reed didnt have a gap between it and the bottom part. The bottom part of the reed had about a .004-.005 gap between it and the cage. Does this sound ok? Somebody told me i could turn the reeds over and this might help it. But now im confused if they meant the actual cage (I dont see how this could make a difference) or the reed pedals. The reed pedals are 2 pieces that look like they are laminated togther. They might come apart with an exacto knife but i dont want to mess them up. Or they might not be made together, its kinda hard to tell. So i cant flip them unless I get them apart. Anybody know if they come apart? Waiting to put it back together. :crazy:

[oldsking86]

You should just need to unsrew the petals off, and flip them alone. If there is a gap without you moving them then that's your problem. They should be shut, or the slightest bit open. Essense is for them to vibrate sothen need a VERY VERY little gap. Take the spacer off you have on there and just put the cage back on.

[InPiEcEs]

If you look at your reed cage, you will see that the reeds are fastened with screws.
You can remove the screws, and turn the reeds over, so the topside is now down facing the cage.
If I were you, I would check float level. If the float is too high, it may run rich, but the level wont be high enough to run out the overflow tube. The 86 had a 34mm Keihin PJ, which is a flatslide carb. The reed spacer is not stock. Stock would be the intake boot, then the reed cage.
As far as your plug gap, I would go no more than .020"

[Dammit!]

Stock pilot is a 42. There's no reason for you to be using a bigger one. I can't remember off the top of my head how many turns out the pilot screw should be but whatever the factory recommends is just a starting point anyway. Start with it about 2 turns out. One method of dealing with the pilot screw is to turn it in until it starts to die when idling, then turn it out until it starts to die, then set it right in between those two points. I personally just adjust for the best throttle response.

You said the needle is all the way down but people have different definitions of that. Is the needle all the way down or is the needle clip all the way down?

Changing jets to as different brand but the same size is pointless.

My recommendation would be to set the needle clip, pilot jet and air screw back to factory spec and then get the main jet dialed in first. Then get the needle clip dialed in, then adjust the air screw for best throttle response. Doing it in any order other than that is just going to make things harder on yourself.

Edit: stock pilot for '86 was a 42. My bad. Factory setting for the air screw is two and a quarter turns out.

[bamatj]

Ok thanks for the replys. Each reed pedal is 2 peices, I can not simply turn them upside down unless i pry them apart. Im not sure they are suppose to come apart. I will try that if they can come apart. Ok on the pilot I started with a 42 no name. I was told that to use only Keihin jets as the other sizes might not be the same as Keihin. I can turn the mixture screw all the way out and it makes no differnece. I would think with a 42 pilot, no air box lid, and the mixture screw turned all the way out. it should atleast be getting close to lean. But its still loading up bad. I cant keep a spark plug in it. I dont think this is a jetting issuse. Because no matter what i do it doesnt make any noticeable difference from the bottom to 3/4 throttle. I cant keep it running or spark plugs in it long enough to get it jetted. Also on the idle adjustment, its running so rich i cant even tell a difference between all the way up or all the way down. The DGH needle is leaner than the CEJ. The clip is all the way up and the needle is the deepest it can go. Still to rich. The slide has some small parts of chrome wore off it. Would the slide cause this much headache? Its a number 60 slide, is this factory? I can get the main get dialed in fine, thats no big deal. A little under 3/4 throttle on up is easy to adjust and Ive had it running great several times. Ok so is the pedals suppose to have a slight gap or none. .005 gap is pretty small.

[Billy Golightly]

What is the spark plug gap and are you losing transmission oil after its ran?

[Dammit!]

I've only run into one 250R that didn't want to run right no matter what we did. Jetting changes got mixed results, tried known good electrical components, different plugs, just nothing worked. It would run ok one minute, shut it off for a few and then it ran like crap again. At the end of the day we decided it had to be a bad crank seal so it went on the trailer. Not sure what the status of that one is right now. It wasn't one of my machines.

[bamatj]

I am around 30 to 35 thou on the spark plug gap. I changed the oil the other day. I went and checked it and it seems to have lost some.

[oldsking86]

Not to highjack his thread, but what would losing oil have to do with it running lke crap? Bad seals inside the block?

[Dammit!]

Not to highjack his thread, but what would losing oil have to do with it running lke crap? Bad seals inside the block?

If you have a bad RIGHT crank seal it will suck tranny oil into the combustion chamber. A bad LEFT seal will cause it to suck air and go lean.

[ceaserthethird]

just buy a new carb 38 , new set of Reed's .... V-force 3

Should be good to go ...

[Mosh]

I agree,IS the pipe blowing out blue stinky smoke???If so the crank seal has let loose and it will kill your plugs.Another common thing that I seen no-one mention is the coil.They are known to go bad from time to time and the bike will not rev up and it will foul plugs.Any aftermarket killswitches???IF so By pass them.I have seen them go bad and partially short the ignition system.

Your jetting seems to be close enough for it to run decent,So I suspect crank seal,Ign coil or a Kill switch.

[bamatj]

Im thinking its the crank seal. I will try to make a leak down tester today if I can find out how to make one.

[bamatj]

Ok done the pressure test. I let it set for 10 minutes, and the psi didnt go down hardly any if not none. I would say under 1 pound. I thought that might be the problem since people brought that up. Guess not. I think this carb is junk. I got 2 more on the way, but I hate the wait. Anybody else got any test or guesses? Im open to ideas, but I have bout ruled out everything else, that I know of anyways.

[Dammit!]

Have you eliminated electrical problems?

[iowarotax]

Ive had the same type of problems on 3 different Rs. I spent 2 weeks on one thinking it was the carb, reeds, air-leak. turned out to be a carboned up pipe, was full of crap. The other was last week, turned out to be very dirty and oily airfilter. Both rs would idle and rev up great, but when I hammered through the gears they would fall on their face and sputter. Both run great now. It wasnt the carb at all. Both acted rich.

[Rustytinhorn]

I second the float level. If it is too high it will make your bike stumble and sputter.
I would keep jetting down until the plug comes out dry and near brown or a lighter black color. Also is your intake and exhaust clear of any blockages?
For the Boysen power reeds, they tend to make the idle jet run rich and the main jet run leaner.
Check the timing. It cannot be adjusted, but it wouldn't hurt to check anyway.
Flatslide is stock for '86 as far as I know.
What is your elevation?
I'm 5280feet, running a 38 pilot jet, and still running too rich at idle.
If good compression and good spark, then keep jetting down.
I'll take it off your hands if you give up. lol

[bamatj]

I have not checked the elec. system yet. I will work on that. I know it can cause all kinds of headaches, but I dont think it would flood like this because of electrical probelms. I will clean the pipe up. It is pretty nasty, but is far from clogged. Or all i can see of it anyways. Air fliter is brand new and clean. Float level has been eliminated. Im at about 2000ft. I cant jet down any further right now. But i will order more jets. No airbox lid, 42 pilot, air screw turned all the way out, DGH needle, 150 main, clip all the way up is as lean as I can go now. I will check the timming, I will look up how shortly. Ive read a little on the elec. system, but that kinda stuff is my weak point. Anything I can do to the elec. system thats simple to check? Thanks for the help guys!

[Billy Golightly]

What psi did you do the leakdown test? 7lbs, 7 minutes. If it drops any, it leaks. If your losing trans oil in a short period of time (a few hours, or days of use) you've got a leak. Either centercase gasket (Common area is inbetween the counterbalancer chamber and the crankcase) or a crankseal.

Gap the plug to .018-.012

I haven't seen it mentioned, are you using the original roundslide Keihin, the PJ oval slide, or a newer style PWK D slide carb? DGH needle...sounds like a PWK.

On the ignition system, download one of Dammit's service manuals, diagnose as per its reccomendatins with an ohm meter to check for continuity on the parts.


In my opinion you've got a gasket/seal leak to the trans thats sucking that in and screwing you up.

[bamatj]

I really need to ride it more I think to see if I have oil loss. I changed it the other day, and when i checked it the next day I did have to add some. It wasnt very much really though. I done the pressure test about 4 times, and its really hard to tell if its leaked any. I need a better gauge to go on it like a 0-15 psi so I can really tell. I will work on the elec. system if the other carb im gettin dont fix it. I guess it will just have to sit a few days. I think its the carb I hope and nothing more. Not the jetting but I think its the pilot system clogged up or the choke sytem is messed up. I still dont understand how I can screw the idle all the way up or all the way down and it does not change the way it runs any. It should make a slight difference I would think no matter how bad it was running if the idle system was working right. So i guess the list of things to do is swap the choke/idle jet off the other carb im getting, onto the one im running now. If that dont work I will change the carb. Next I would buy a smaller gauge for my pressure tester so I can tell more about it. Next would be new reeds. And then the ignition system. Oh yea the carb is a 34mm pj, with what i would call a flat slide. I will get it right maybe in a few days. I just dont like being defeated for the time being. I think I am going to go beat the hell out of the idle adjustment right now.

[bamatj]

Been messing with the carb. The idle adjuster seems like it would work fine. Same for the choke. The only thing I might question is the slide or the if something is wrong around the slide base and the brass tube the needle jet goes down in. Im about stumped. Also unless im missing something turning the mixture screw out makes it richer not leaner. If not somebody is going to have to explain that one to me.

[Billy Golightly]

When the airscrew doesn't do anything, your pilot is the wrong size. When you turn the airscrew out, your making that particular circuit larger, allowing more air to travel through which is leaner. The airscrew is a tapered needle like thing that goes down the side of the orifice, the further you turn it out, the bigger it makes the hole. The further in, the smaller. I mess with pilots all the time on my carbs, If you don't have a crankcase sealing issue then you probably need to lean your pilot out or at the least remove inspect and clean it and the circuit it goes into.

[bamatj]

I going to order the smallest pilot I can, just because it would be a good testing tool. Heres what I dont understand, not trying argue just trying to understand the carb better. From the pilot jet, I think they are 3 passages out of the float bowl. One is the small hole cut on an angle on that comes up into the bore of the carb on the engine side of the slide. The other I think is the small hole about .010-.015 dia. that is under the slide. Im not 100% thats from the pilot or only the pilot kinda hard to tell. The other goes to the mixture screw. It goes to the back of the carb. It travels through the ''seat'' of the mixture screw. After it goes through that it goes into the small bore back to the needle and main jet. It comes out around the main jet needle. The only way turning the mixture screw out leans it out is if it makes some other circut do something. Or it means that the pilot jet is getting air from the float bowl. You can try this by closing the mixture screw all the way off, then blow on the pilot jet and start opening the mixture screw up. Then you can tell the further out the mixture screw is the more gas it gets from the float bowl. So where does the air come from that leans it out? Maybe my carb is missing something. Anyways the best I can tell the choke/idle circuit should work fine. Sorry im not to good at explaining things. Im not saying turning the mixture screw out dont lean it up, Im just saying i dont see how.

[Billy Golightly]

If you get the smallest pilot you can find, it wont start. I at one time liked to run about 2 sizes leaner pilot in mine then what it needed so It wouldn't load up on me any while I was staging at the races. This worked great, the bad thing was it took like 15 kicks to get it started. I went from my #45 pilot back to a #55 and it cranks on half a kick almost every time now. It does load up a little bit if you let it idle for a long time, but thats better then standing out at the line kicking your brains out in the heat.

Your description of the carb is kind of confusing to me...just take it off, and look at the back of it where the airbox/filter clamps on. At the bottom of the venturi there is a couple small holes, and you'll see the end of the air screw sticking out into that orifice

[bamatj]

Yea its confusing to me to lol. The only thing im saying is opening up the air screw lets more gas in. I figured the smallest pilot jet is way to small. What I meant by using it as a testing tool, if you was flooding real bad on the bottom side you could pop the smallest jet in there, and if you was still flooding you would know it wasnt because of the pilot system.

[hondared]

Had an identical problem with my 86 250r and I too was was completely baffled because the issue started rather suddenly. I suspected a dirty carb and took it apart totally and blasted it with carb cleaner at least 5 or 6 times to no avail. I eventually shined a flashlight into the base of the needle and seat (it must be removed) and found a piece of dirt in there that the carb cleaner would not remove. Upon cleaning that it ran excellent. And no, gas was not pouring out the float bowl overflow as you would imagine. Just be sure to go back to your original jetting, where I assume your trike ran fine. With all the adjustments you've now made, it may not right right even with a properly functioning carb.

[bamatj]

Actually I have yet to see my trike run fine. Maybe someday though. The needle seat on my carb is non removeable. But it may be a piece of trash somewhere I cant get to, but Ive gave up on cleaning it, I have already done the best i can do.

[hondared]

The needle and seat is removable by sliding out to one side the small diameter pin that the assembly hinges on. Just be careful to not lose the spring. I'd be willing to bet that this is your problem 'cause mine acted exactly the same way. It just could not handle all the fuel it was getting at low rpm's. Fouled plugs instantly. If you want step-by-step help on the needle and seat thing and proper jetting let me know. Let's get this "R" running!

[bamatj]

The seat in mine is pressed in. The needle and seat do not leak air. I have tried different levels for the float. Its not the float level. Im not real sure what it is. Ive cleaned the carb the best i can. Can anybody tell me if a 60 is the stock sized slide? Also what size is the factory choke/idle jet? It may be something wrong with the choke/idle system, but it seems to work fine when i take it apart and test it.

[hondared]

The slide in mine is a 60. Not sure the size of the pilot. I'll have a look later today.

[bamatj]

Ok thanks, good to know the slide size, I was begining to wonder if it was the factory one.

[hondared]

Pilot=42 Main Jet=150 Jet Needle=14 6 8 Altitude=800 feet
Runs like brand new. I'm not understanding why you cannot remove the needle and seat assembly.

[bamatj]

I can remove the needle, I will try to get a picture of the seat.

[hondared]

Yeah a pic is worth a thousand words.

[bamatj]

I made a few mistakes. The DGH needle is a richer than stock needle. And the lowest I have for a pilot jet is a 42 (though the 42 is not a keihin), not a 48. Like I said though I dont get much of a response in the jetting changeing needles or clip postions, or even the jets.

[hondared]

The stock needle like I run is what you should have. You seem reluctant to believe me about crud under the needle and seat so other than that all I can suggest is a spark plug cap and wire. I believe the plug wire is one piece with the coil, and these machines burn up coils more than most, so changing it out doesn't hurt either. Like I said earlier, my 86R flooded itself something fierce at idle to mid rpm too, until I cleaned out that crap which was not easy to find. You won't find a cheaper fix than that either.

[bamatj]

Relucant to believe you? I have cleaned and cleaned the carb. Is something somewhere i cant get? Id say that its possible. But i dont think I can get the seat out without screwing up the carb. I will try to get a pic.

[BigRedRunner]

Why is everyone making a HUGE deal out of the needle and seat. Reassemble the float bowl, put a small section of fuel line on (preferably clear), , dump some water down the line and see if it holds once the bowl is filled. Wiggle and the tip the carb a little to simulate riding, and if it holds, you're fine. Take the float bowl back off and let dry.

[atcsteve]

Why is everyone making a HUGE deal out of the needle and seat. Reassemble the float bowl, put a small section of fuel line on (preferably clear), , dump some water down the line and see if it holds once the bowl is filled. Wiggle and the tip the carb a little to simulate riding, and if it holds, you're fine. Take the float bowl back off and let dry.

There is a guy who has done this a time or two!!!!!!Good advice!:Bounce

[Daddio]

Could the crank case possibly have excess oil or oil fuel mixture lying in it from a leaking carb, like from before you cleaned yours? I've seen this happen before.

[bamatj]

I have checked the needle by blowing air in it.(with my mouth lol). Yes that is possible daddio and something i havent thought of. When I first got it, it was running to rich on the bottom. Then is started getting worse and worse. I didnt think it would be no big I figured I would just rejet it. I was wrong about that, this has turned into a headache I cant figure out. One day I got a piece of trash in the seat and she flooded bad. It was pouring gas out all the overflows in the carb. So you could be right daddio, im going to check that right now. If thats not whats wrong with it I will still keep that in mind. I dont think I would have ever thought of that. Thanks for the help guys.

[bamatj]

Ok I checked it out. There seems to be a little bit of fuel in the crankcase. But I dont think enough to cause problems. I blew it out, and it would come out in puffs, didnt sound like there was any liquid in there. I ran a small hose to the bottom and blew it out good for awhile though. But I think i might have found something I over looked in the carb. Is the needle suppose to bottom out on the main jet no matter what clip you have the needle at? I assume thats one of the reasons the needle ''cap'' is spring loaded so the it will let the slide travel on down even when the needle bottoms out. Mine barley touches the jet even on the highest clip. I cant believe I just now caught this as much as I have messed with the carb. It doesnt seal off good the way it is now. You can hold the needle down on the main jet without the slide and it seals fine. Except the needle that was in it when I bought it, it dont seal off no matter what. Its one of the silver needles. Im not sure if it was junk to start with or just wore out. So like I said the slide is a size 60, but are they different from bigger carbs? I bet this one is out of a larger carb. If somebody has their carb apart can they see if the needle bottoms out even on the bottom clip? It will be this afternoon before I can work on it but im hoping this is whats wrong with it. Maybe my other carbs will be in soon, but if this is whats wrong with it I think I can fix it so I can ride some this weekend.

[hondared]

It looks like it does bottom out on the main jet or at least is very close to it. Overall length of my jet needle is 2 5/8" tip-to-tip. It's in a Keihen PJ oval slide carb.

[bamatj]

Well my carb still hasnt come in (thanks fedex). Ok I need somebody to do a little test for me. I need to know for sure if the needle bottoms out in the main jet no matter what clip its in. Put the clip in the top postion, then put the 6mm spring loaded bolt back together. Hold the slide all the way down with your finger. Now try to blow in the main jet. Now do the same thing with the clip in the bottom postion. If somebody can do this for me I owe them big time. Im cutting on my slide and Im gonna make some spacers so I can tune this thing in. If this dont work then im fresh out of ideas. Thanks!

[bamatj]

Well I finally got my carb in. Im not sure what was wrong with the other one, unless it was the slide. Ive got the new one on now and im getting pretty close on the jetting. The only thing I dont like about it is it has a #40 slide in it instead of the stock #60. Im kinda having to fight to get it leaner on the bottom, and not lean it out so much on top. Im running a 42 pilot, DGH needle in the 2nd clip postion, and a 165 main. I still got just a little bit of tuning to do on it but its running so much better now. I shouldnt have fought so hard with the first carb that thing was junk, but I learned a little bit anyways. Thanks everybody for the help.

[Rustytinhorn]

Is there an update for those of us still struggling? Haha

[bamatj]

Well it was running good. The other carb solved all my probelms. I never did figure out what was wrong with the one that came on it. It was kinda hard to jet because everything was a little bit different and had more effect in changes than all the graphs Ive seen. I guess that might have to do with the #40 slide. But now Im having more problems. I think it may be the timing not advancing right or something. It runs good, idles good, and revs out good. But Ive lost tons of power. I still have great compression, and no air leaks. But I havenet had much time to work on it, maybe soon. I got me a new service manual so that should help. If I dont get it right soon i will start a new thread.

[Rustytinhorn]

Ya, let us know. My 250r is the same way. tempermental. I'll think I have the jetting near perfect one day, and then I'll try to go for a ride the next day and it gives me troubles all over again, and I get mixed results every time I try to work on it.
Just curious if you switched gas octane or the station you bought your gas from lately. I was running 85oct from the pump and then decided to try some 91 or 92 octane from a different station. It actually made it run a little worse on the top end until I put the 85 from the first store back in and it cleaned it back up a little.

Back when my bike was running 120psi I tried some 110 aviation fuel once, and didn't notice any difference from the 85. I replaced my head gasket and got it up to 150psi, and every once in a while when running the 85octane at WOT I think I can rarely hear a predetonation or two. I'm gonna try some 87oct. next just to see if it is predetonation or just piston slap.
Either way, good luck,.