Runs like $hit after a half hour or so

[Hypo]

I clean the filter change the jetting, run it a couple times up the street and it runs great. Revs clear throught the powerband and everything. I go to the trail and it will run good for like half an hour and it starts sputtering like its getting watter in it. (its not dry as hell out). It breaks up and makes like a (buuurrrrrr) sound and occasionally making a normal sound back and forth if you can imagine that. If I burry the throttle in gear under load if makes the burr and never clears up. It will get so bad at times that the only way I can ride it is to bearly be on the gas and let it slowly clime the RPM'S. It seams to rev more freely in nuetral but it still sputters a bit but not as bad as when I'm going. I get so mad at it I just want to keep the throttle pinned and blow the f*cking thing up but it just goes buuuurrrrr sputter burrr.

 

I dont get it. I thought the jetting was off and I was fouling plugs, but if I change plugs real quick at the trail it doesnt change. It runs so bad that Ill end up with oil all over my pipe ends. I cant figure this out I come home and in a day or so Ill clean everything filter and all and it will rev clean and run real strong again for the 1 minute I can run it on my street. Ill put it away thinking its fix then go riding again and same shit.

 

I had this problem for a while and I dont know what to do. Ive changed CDI, Coil even though the first one tested good. Im running a 200w stator from RS. Which they said tested good but sent me a new one that tests the same and does the same shit. Ive even changed the wireing harness. I still think it may be the RS 200w unit. What do you guys think.

[AKheathen]

I disagree...you set the mixture screw for the proper air/fuel ratio. I agree it works until 1/8 throttle.

But...once the mixture is correct, then you set the appropriate idle speed (1400 to 1800 RPM).

 

When the mixture screw is set correctly, you will get your highest idle, but then you adjust the idle screw to the appropriate RPMs.

 

From what you wrote (or how I read it) you're telling him to set the idle speed screw for the mixture....like I said, how I read it.

 

That is incorrect...if that is what you're saying....

 

Sorry if I'm misquoting or misunderstanding what you're typing.

sorry, i was really tired, and diddn't word it right. i do agree with you on how to adjust them, but it was part of the troubleshooting process, and i was thinking about someone elses problem and thaught they were oversized juggs. should still see what the airscrew does with theslides higher and lower. it sounds like the needle's not fitting right. or if the pilot's too small you may need to load it with fuel to stop the hesitation when you stab the throttle.also, reading back, i noticed you don't specify all you did in the rebuild, or what you did for mods (intake and exhaust) did you port? domes? pipe? can? boost bottle, tube, or plugged? and a biggie i forgot- is there any exhaust leaks? i'll try not to post when i'm tired, but puzzles keep me from sleeping.

[fastbanshee8]

Try putting new spark plug boots on. They're only $4-$5 each. Unscrew the old ones, cut back each wire 1/8"-1/4", and screw the new ones back on. Plug boots can, and do go bad. Almost anything electrical going bad, acts a lot worse once it starts getting hot. It's a cheap easy fix, and if it doesn't fix it, you haven't wasted a lot of time, and money eliminating them as a problem.