Motorcycle Repair: ct-90 valves, combustion chamber, adjustment screw

Question
I have a ct-90 (one of the 70's years not sure which, most likely early model) and I think a valve is sticking or somehow broken. Even with the valve adjustment screw completely removed it still kicks fuel back out of the carburetor (as if the intake valve is open during the combustion stage). Do you have any suggestions on fixing this or can you tell me how I can get a better look... maybe can you tell me how to even replace it if I have to. Any information you have would be appreciated thanks.

-William.

Answer
William, the valve could be stuck or it could be bent.  It will require pulling the head to fix this.  There isn't much room in the combustion chamber for a valve to stay open with the piston, so I'm guessing it's bent.  Pulling the head is easy on those little bikes.  Just be real observant as you are taking it part and make sure you see how the cam is timed so you can get it back together.  I get a lot of questions about how to time the cam after it's all apart.  The "O" is away from the crank when the piston is at top dead center.  Just be sure and check it before you pull the sprocket off.      

Regards
Rich