Not so much that the intake valve sticks open. More likely the valve face and seat are worn which basically, the valve clearance closes and get held open.Thank you so much for the great information! The engine numbers are in a photo, as well as some longer views. The videos you sent are more than excellent, and from Bald Eagle 242's commentary and additional video, I think I have found the actual problem keeping this engine from starting and running. When I sprayed in some ether, it only popped at the intake. Didn't try to fire. I now realize it's likely that the intake valve is stuck open. I suppose we will need a head gasket. Again, thank you!
On an additional note:I'm working on a rototiller a friend got at auction. It ran fine at first, but quit,and can't be restarted. It pops out of the carburetor, but won't really fire. We suspect fuel inlet needs cleaning, but the carburetor is mounted directly to the top of the tank. I haven't seen that design. Anything I should know before I start into it?