So last summer I rode alot but the quad seemed to burn alot of oil so I stopped riding it as much, but also any time I had it running it had a knock to it it that sounded like valve knock, I was told to adjust valves but im not sure how to adjust them on this quad to I didn't bother it, I just stopped riding it, I pulled it out a couple of months ago to ride it and it wouldnt idle on it's own but if I got into the gas too much it would cost down and die, so I put it aside for a couple months, now im finally getting back to it and I can't get it to start, pulled the plug and has spark, has gas but won't fire!? I pulled intake off and when I crank it air comes out of the carb along with old winter gas, I haven't got it to fire one time since pulling it out of the shed but I ran a compression test on it and it didn't even read, it would fuck the gauge alittle but didn't get anything, I assume because a valve is stuck open and all the compressed air is escaping through the carb? Can anybody help me out? Could a valve just need adjusted or be stuck open and if so how do I adjust them on a shim under bucket system?