Appatchie 100cc quad what's my problem ?

Iv got 2 appatchie 100 quad both was working 1 works fine. Other stoped working it ticks over but when rev it cuts out. Iv tryed carb reed block airbox Cdi coil and put a new plug init still no go still dose same what's my problem ? Could it be piston rings ??? Carb manifold fine aswell no cracks no holes in engine. What's the problem 07768721866 let me no ur ideas plz