Engine Problems...

[Jekyl_22]

Ok, after almost 5-1/2 months, I got my four wheeler put back together today. I had some problems. It seemed to run fine, but towards the end of the day, it started cutting out. What could be some causes for this? Also, what kind of jetting should I run if I have the following: IMS 440 (11:1), White Bros. Race Cam, Aftermarket CDI (+1000), and a K&N Airfilter?

[Jekyl_22]

Well, I tried a 180 main jet. I seemed to work out really good, about what size pilot jet should I use then? Any help is much appreciated...:ermm:

[KY Woods Rider]

I have one question... Did you use the Cometic head gasket that comes with the IMS 440 kit? If so, you may have blown a head gasket. There have been numerous complaints about the Cometic head gaskets.

Since you said that it seemed to run fine at first, but later it started to miss, it sounds like it is either electrical or you developed an air leak (probably the head gasket). If it was a jetting problem, then it would have started as soon as the motor got up to opertaing temp, if not before. I'm going to take a wild guess and say that it misses the worst when you accelerate out of a tight corner. If so, then it's almost certainly a head gasket.

As for jetting, you didn't say if you were running the stock airbox lid or if you had removed/modified the lid. A 42 pilot should be pretty close with the air screw about 2-2.5 turns out. A 45 pilot might work better if you ride when it's pretty cold outside or you are at a low altitude. Raising the needle one position (lower the clip) should be about right for most conditions (no lid in cold weather and low atitude might possibly require two positions). A 180 main jet seems too big to me (if it's a Keihin jet, I don't know anything about the ones from a jet kit), but if it works good and a plug check says it's okay, then go with it.