Out riding this weekend and my sons 90 died. It cranks over fine, with starter and kick start, pull the plug and it sparks when placed on the head. Plled the carb and cleaned it up, didn't look dirty inside. It fires once in a while but sounds like it might be firing out of time. Is there a chance the timing could be off. I haven't looked under the stator cover yet but was wondering what I should look at. I'm going to pull the carb again and spray it down real good and blow air through it.

It is modiifed with a Kiehen 24mm, carb, KOSO pipe and intake.

 

Sounds like you might have some broken reeds.

 

I don't know. Ours has always started fine. However a couple of weeks ago we went to ride and had a starting problems. It fired up fine and we took off. Made it about 50 or 100 feet and it died. I tried to start it forever before it restarted. It's done fine ever since. I've read that the auto choke on the carb can cause problems sometimes. Maybe that's it.

 

Pulled the reeds and they look fine.

THe auto choke is gone, its got a Kiehen 24mm carb on it now.

I'm gonna grab a can of carb cleaner, soak it and blow it out really well.