Motorcycle Repair: Honda xr50r dirt bike

Question
So there is a honda xr50r dirt bike in my engine tech class and it won't start. It has spark and compression and the kill switch is not on. It won't start with starter fuel sprayed in it either. I feel it may have something to do with the timing because we have the carburetor cleaned out and timing is the only thing I can think of that would be wrong with it. How do I adjust the timing and what do you think I should do?

Answer
Grant, Its possible the timing is off but it wont be the ignition timing,unless the flywheel key is bent throwing the timing off its pretty much set. Turn the engine over by the flywheel and watch the intake valve close. Make sure the plug is out so it will turn over easy. Use a small screwdriver or pencil and poke it down into the cylinder and feel for the top of the piston and turn the flywheel untill you fell the piston at TDC and look at the flywheel and see if the timing mark is on the pointer. If it is then look at the cam sprocket as it should be at the top of the cylinder head and maybe a mark or line in the opening for the cam sprocket.If this off you will need to pull the chain tensioner out to loosen the chain and turn the sprocket untill the marks line up then put the tensioner back on and see if every thing lines up now. Also make sure there is some valve lash there. Honda does not use much so try about .003 to .004 gap now see if it fires.