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Published on Jan 18, 2011
I made an adapter that allows me to pump air into the engine using a bicycle pump. Since I felt very little back pressure, I suspected there was a compression problem, which I verified by using a compression leak-down tester.
FOLLOW-UP: As expected, the valves were not closing (especially the exhaust valve). After shooting this video, I pulled the head cover, removed the valves, lapped the valves in, and ground the valve stems slightly shorter to provide the specified gap (.004 intake and .008 exhaust). After re-assembling, the snowblower started immediately and runs very strong - actually better than new. It's still a bit of a mystery why there was no gap, since the valves obviously did not grow longer over time. Perhaps the valve seats wore down, which sinks the valves deeper into the head. Anyway, all is fixed now - it runs great. Very powerful, and doesn't bog down at all.