Please help

[Magz]

recently i bought a small chinese quad from a friend really chep ($60) because he couldn't figure out what was wrong with it.
it cranks but does not start.
after about 2 days of messing with it i got it to start but i still don't know what is wrong with it.
when it started i removed this bolt and it started right up, when i put it back, it doesn't run.

When i remove the bolt this cover pops out a little and rotates slowly

Also when it is on it only runs with the choke on, if i take it off it dies immediately.

Could it be the timing, or valves.
I have been reading a lot on these and i was thinking the valves might be too tight.
thank you 

[Krandall]

Hmm, This is only an educated guess. but that one on the lower side appears/sounds like it's the cam tensioner....

[Magz]

Hmm, This is only an educated guess. but that one on the lower side appears/sounds like it's the cam tensioner....

If so what could be my problem? How come it runs with the cam tensioner loose? how do I fix it.
Thanks

[Peelz]

Sure you are not having carb troubles, and doing this is actually adjusting to help faulty carb? I say this because I just spent a whole day adjusting my son's carb. Idle screw and idle speed. Runs well now.

[Magz]

I have two other mini quads, i'll see if one of the other carbs is interchangeable.
Checking the carb is a good idea.

[Magz]

It was that the valves were too tight, running like a champ now.   

[Peelz]

It was that the valves were too tight, running like a champ now.   

sweet!

[Flynbyu]

You got it for $60.

Sweet.

~Brian

[Peelz]

Please allow me to welcome you to the thread and the forum,Cheap Air Max 2011, I anticipate many enjoyable conversations ahead.

I anticipate butsects.