ok im geting a prairie 400 running for a friend of mine he got it with the tank and seat off and the dude never told him wats wrong with it. it has spark, it has compression, and im giving gas and even starting fluid. all it is somtimes blow some smoke out side the tail pipe and back fie thru the carb it just goes pop and some fire comes out of the carb. im pretty sure that the intake valves are open when it sparks so is there anyway to set the valve timing or spark timing??

 

Have you checked the valve clearance. If the intake is too tight, itll be hard to start, but should show up on a compression test. Spark timing isnt adjustable, and unless someone had the motor apart, the valve timing should be ok.
Lean will cause the pop out the carb too. Have you cleaned the jets in the carb yet? The idle jet is the one to focus on, as itll be the first to plug up, due to the tiny center hole.

 

well i double checked the compression and it wasnt as good as i thought. so after some more tryin to get runnin i re adjusted the valves and then i noticed smoke coming out of a rad hose so i tried it some more and yes it was fuel and air blowing out of the water pump rad hose so i guess its has a blown head gasket and i took the head off and im wonderin if u guys know anywere to get new gaskets and maybe some new rings? if i already have the head off ow much harder is it to pull the piston out and replace the rings? and one mroe thing lol u guys know anywhere i can get step by step insturctions on how to put it back together the right way?