So I’m new to the forum looking for help I have basic knowledge as I am an auto mechanic but my China quad 107cc unsure of the brand will not start has spark clean carb clean fuel but it spits it out from the filter when trying to start the timing marks all line up and the valves are adjusted does anyone think it could be the timing or a head gasket I want to be sure before taking the engine apart

 

Compression is usually over 100 on the 110cc. The head gasket may be blown. They sometimes leak in the area with the channel that leads back to the engine case so it ends up pressurizing the engine case and not causing oil to leak on the outside of the head. I’ve also had the idle jet in the carburetor be clogged a couple times. The hole is so small it takes almost nothing to clog.