I'm stuck, and can use some help. Son's 250R was running kind of rough last time we rode, but I thought it was due to a top end going since I shimmed it a couple times. I replaced the top end, and also put in a new piston....and the bike won't start. Got it running by pushing it, and it was running pretty rough. Thought it might be a dirty carb....so I took the bike apart, and thoroughly cleaned out the carb. The bowl of the carb was good, but the top end where you put in the needle had some slimy mud probably from pressure washing. Cleaned it thoroughly....put the bike back together, and still running rough. I can push start it to get it going but it wont idle without continually hitting the throttle. If it stops, it won't kick start. I do have a new spark plug in there also...the air filter is clean. Could it be the CDI module or the spark plug connector assembly? I double checked the timing, and I know the shims are right on. It does have good compression, so I know the piston is in there right, and when I can get it going it will pull normally. I don't know what to check next. Thanks for any help!!!