Whoa... sticking valve? Not sure if you want to do this with a hot engine, but next time ya might pull the plug & test for compression. With something other than your thumb of course.
I'd guess a sticking exhaust valve would keep the piston from inhaling enough fuel/air mix from the intake valve. And then the stuff would just be pushed out the exhaust valve and there would be nothing compressed for the plug to ignite.
If it's a bent valve, it could be catching part way open when hot, then letting loose when it cools. It might just keep moving while the engine is running fast, but have a chance to stick when slowed down due to lugging the engine.
I'd guess a sticking exhaust valve would keep the piston from inhaling enough fuel/air mix from the intake valve. And then the stuff would just be pushed out the exhaust valve and there would be nothing compressed for the plug to ignite.
If it's a bent valve, it could be catching part way open when hot, then letting loose when it cools. It might just keep moving while the engine is running fast, but have a chance to stick when slowed down due to lugging the engine.
