Those chain saw 'piston stops' often won't work on sidevalve 4-stroke engines, due to the plug hole being positioned away from the bore.
The other old piston stop lurk; that of feeding a soft [e.g. cotton] cord into the combustion chamber via the spark plug hole, can work OK on these, though.
Cheers,
Gadge
"ODK Mods can explain it to you, but they can't understand it for you..."
"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."
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