I am having the same problem. Could there be something stripped in the lower case?

 

Original poster

We're now pretty sure that the problem is at piston. Which of course requires an engine removal and cylinder head removal. We had a friend-of-a-friend who owns a couple of these ATVs look at it and he said it's the piston. So when I get the quad back from him, and have a couple of spare hours, I'll start pulling the quad and it's engine apart.

 

how much compression should these engines have, i have a 50cc kazuma with the same problem? thanks

 

I have never checked mine but would think 100 - 110 would be enough to run... 125 would be better.

 

I am having the same problems. A lot of back firing and now have nothing.. going to bring it in to see if it still falls under warranty. I think they are going to try and give me the run around. So if anyone has any idea of what is going on with it please let me know

 

Check to see if you can rent a leak down tester from a local auto parts store. You will also need an air compressor as well. If you can't, then you should just buy a new motor. I will be less expensive. about $225 - $250.

 

+1 on a new motor

 

a compression tester??? I have one not getting any compression at all

 

Do a compression test and if it is bad just buy and install a new motor. That is the beauty of these Chinese units~!