I recently picked this quad up and at first it wouldn't start at all. I rebuilt the carb and also put in new rings as compression was low. Now it will start but only if I pull it with another quad. The compression still seems low but the rings are new and I looked at the valves and they seem to be working correctly. Once it starts it will run strong but won't idle. If I let off the throtle it will die. Also it is kind of noisy at the higher rpms. It sounds like there is plenty off power, but really it doesn't have much. Once it gets going it really has plenty of power at the high end just no "get up and go". I really don't know what to check next, so any help I could get would be great.

 

Did you do the rings? Do a compression test