Any chance of help?

[dag1911]

I bought a little 250 for my wife and we took it out right after that and it ran great. Came back to the shop, parked it for about a week or two with a few starts in between, and then went out over the weekend and it started cutting out and backfiring into the carb. It seems like the choke was sticking cause it was "loading up" and you'd have to give it a bunch of gas to get it running again. It won't idle while in gear, or in neutral for that matter. It runs for a few seconds and then will backfire and die. There was a bit of smoke that would come out the top of the carb as well. When I'd have it running and in any gear, I'd take it up to about 3-4000 rpms and you could hear it cutting out a bit. No pattern to it, just random cutting out. However, when going through the gears at full throttle it ran fine.

Since, I have rebuilt the carb with a Shindy rebuild kit. Everything went in fine and even put in a couple new diaphragms. I cleaned the carb bottom to top, it sat in solvent for a couple days. It should be like new now but the problem still persists. I need help, please!

[wylde1]

I am not a mechanic so I really cant say for sure, but it sure seems like a carb problem to me. If there is any way to do it I would maybe try a different carb to see if that changes anything.

[oxidized_black]

if you are getting good fuel supply and good spark, i would take a look at the valve lash. could be out just a bit ...

[marioweldinginc]

if you are getting good fuel supply and good spark, i would take a look at the valve lash. could be out just a bit ...

If this is the lt250r its a 2 smoke. If its not then Im just real tired lol

[dag1911]

I am not a mechanic so I really cant say for sure, but it sure seems like a carb problem to me. If there is any way to do it I would maybe try a different carb to see if that changes anything.

I have no spare carbs for this wheeler sitting around...or else I would try it. That is why I rebuilt the carb for $40 though! I cant afford a new carb.

[dag1911]

if you are getting good fuel supply and good spark, i would take a look at the valve lash. could be out just a bit ...

I cant be certain on the fuel supply. As I understand it those petcocks are junk on Suzuki's in turn, that is why they put on a good ol Yamaha petcock. So I am replacing the petcock tonight to get rid of the "prime" and blocking off the vacuum port on the carb. Hopefully its a fix. If not, I will look into valve lash. Thanks.

[dag1911]

If this is the lt250r its a 2 smoke. If its not then Im just real tired lol

Definitely not a 2 stroker smoker.

[bansheedave]

Solvent is your enemy. If you soaked it in carb cleaner, chances are the internal seals inside your carb are shot. Bad gas cam also cause carb issues. Could be valve adjustment issues, stretched cam chain. Just a few ideas.

[dag1911]

What kind of seals are "inside" the carb? I have replaced all the o-rings, the float bowl gasket, new jet needle diaphragm. It starts with just a tiny tap of the starter, it idles like a champ, just starts to cut out at about half to full throttle. Is that coil related? Just not getting enough spark?

The gas is fresh and clean. How do I go about adjusting the valves? Are there any repair manuals that I can download off this site? Thanks for your help and ideas...its appreciated.

[bansheedave]

What kind of seals are "inside" the carb? I have replaced all the o-rings, the float bowl gasket, new jet needle diaphragm. It starts with just a tiny tap of the starter, it idles like a champ, just starts to cut out at about half to full throttle. Is that coil related? Just not getting enough spark?

The gas is fresh and clean. How do I go about adjusting the valves? Are there any repair manuals that I can download off this site? Thanks for your help and ideas...its appreciated.

Have you checked all your grounds to be sure they haven't rusted? All your wire connections good? If you don't have a service manual, you should get one. You could have a weak spark, but its hard to tell without knowing all the values of the components and checking with a meter. Some valves need shims for adjustment and some have a nut you loosen and use a feeler gauge to check.

[dag1911]

I have checked the grounds, which there arent many, and they looked good to me. However, I could be missing one some where? Do you have an overview of where all they might be so I can see which ones I have hit? All other connections seemed to be good but didnt go over them with a fine tooth comb. Perhaps the next step IS to look into a service manual. I didnt want to have to tear this hummer down already...

[MNATV]

I would first check compression or do a leak test if you can. Another thing to check is the coil. A coil will put out enough spark at low rpm to run at idle but not provide enough spark at higher rpm.

[dag1911]

Ok that is a good plan as well. I can check the compression and do a leak down test on it. The more I think about the scenarios and troubleshoot it...it seems likely that the coil is bad. I printed out the sheets from the manual I downloaded to test it. So that is on docket for tonight as well. Hopefully that will clarify things for me. Thanks for the input.

[dag1911]

So I thought I would give an update as to where I am at on this issue I am STILL having. I have tested the coil and it came out in the correct ranges. So that should eliminate a bad coil/spark plug cap. Over the weekend I bought a new CDI box since I didn't have a good way to test it and don't really know anyone where I live since I just moved there.

I put the CDI box in, same issue as always. Starts and idles just fine with the choke on. Take the choke off after it is warmed up, it idles fine for a bit then just dies like its gasping for air. After that I start it back up, put the choke on, give it throttle to halfway, it stumbles cutting in and out without dying. It does that clear up to full throttle. RPM's up to say 7000 and back down to 2000. Just a vicious cycle. So obviously the CDI wasn't the issue.

Also I did a compression check, I am at 190 psi and the lower service limit is 171psi and standard is 199psi. So my top end is fine. I checked the valves and they were in the correct tolerances on both intake and exhaust.

I truly am at a loss right now. Can you guys give me any other ideas to try next?

[bansheedave]

How is the flow of gas from the petcock to the carb. Maybe it is partially plugged and not allowing sufficient flow to the carb. The bike maybe draining the bowl faster than it can refill it.