I have a new item for you to check for wear or looseness.It is the back sprocet.I was ridding and i heard the chain slip and i thought it was the trans at first.When i got off the quad and looked , my rear sprocket had
come apart in 3 pieces.2 of the bolts were gone. 2 snapped off.I looked at the rear axcel and adjusted the chain just the other day and didnt notice the
bolts gone.they unscrewed from the hub because they are 2 sided studs.the keepers dont do sh@t if they unscrew from the hubs ,so check yours good!!!!
Im putting in stainless bolts and locking nuts on the new sprocket so i wont
have this problem agin!!!

 

I would'nt use stainless steel bolts
on the rear sprocket stainless is soft
and will break with that kind of force
use a grade 8 bolt

 

I too had the bolts loosen but saw it before any damage was done!! I lost three studs and one of the locking tabs, Have since put in new studs with lock tight and havn't had a problem.