ok so its been running great up until the other day at sand lake when i layed into it and about halfway threw the throttle it just starts cutting out coughin and spitting and sputtering and now it does that every time i give it more then half throttle?

any ideas i already re-synced the carbs that didnt do anything it will idle fine and run good until half throttle

and no the check belt light is not on that already happened a while back

 

How is the cylinder compression?
Runs any better with the choke 50% on or air box lid open (but not both together)?
Check cam timing as well. The chain might have skipped a tooth or 2 on the cam sprocket. Then, it would start/idle ok but would not run well after that.

 

make sure the chokes are opening all the way
Clark