# Tecumseh HM80



## goball (Sep 25, 2006)

Engine is mounted on snowblower. Engine has always backfired through the exhaust. Exhaust vavle was badly scored and loose in block. Installed oversized valve which helped but still backfires a little and won't start without chock/prime even when hot. Suspect a design or internal fault but can't identify. Carb cleaned and overhauled Any ideas? Thx


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## big ed (Jul 29, 2006)

did you recut the valve seat and lap them to match surfaces together its an important step when doing valve work the seat may have been damaged it could also be a slightly sheared flywheel key altering the timing and causing the back fire and if its got points in the ignition system that opens another chapter a bad condensor will also cause back fire good luck


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## goball (Sep 25, 2006)

Removed flywheel and key was in good shape. This engine has the electronic timing style so timing is set by coil stator to flywheel gap. Set at 0.0125" in this case per instructions if I read them right. Valves were relapped. Thx.


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