did you cover the air filter? or remove the air cleaner ass and cover the carb?
if you covered the carb and if didn't shut down then you must have an air leak someware.
If you covered the air filter that is a good way to force dirt to get sucked into the engine.
Nothing wrong with stopping it with the flywheel.
does the glow plug have the washer on it?
gesh hope you got it running by now.