Last month I bought my son a nice condition 2004 Panterra 90cc ATV. It was sold by Pep-Boys back then. This week I found a beat up one on E-bay for sale locally. I bought it to have a ready supply of parts for my son's but I may be able to get it functional again. Currently the engine is removed and the transmission and stator covers are removed. The seller says that the engine does run but the ATV doesn't move more than a slow creep. I'm going to get the engine put back together and see if it will run and then figure out what is up with the clutch or transmission. Worse case I'll use it for parts for our other one but I hope to get it functional to have another one to ride. The engine is the common clone of the Honda 70 from the 70's.

 

Parts bike, nice. Running parts bike, even better.

Sounds to me like it is a clutch issue.