I have a 1996 300 ex, has been rebuilt top end, at 1/3 throttle and above it sputters real bad, have change carb, have tried different coil, it runs perfect at idle and good takeoff torque, Dont know how to check cdi , battery is chargeing lights and nuetral lights are working
please any suggestions
thanks

 

Did you double check your cam timing? I put a 300ex back together and was one tooth off, on the cam timing. It would let compression come back through the carb, thus making a sputtering sound.

 

I will double check it, the sputtering is engine skiping, might be a beter description
thanks

 

Seeing how throttle input is related to the issue..sure sounds like a carb problem. Are the connections on correctly and tight , at the carb?

 

I double checked the timing chain its ok

 

I agree i think is the carb but changed it with a known good one and also looked the boot over good
thanks