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Old 05-18-2019, 09:42 AM
tenders tenders is offline
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There are two scenarios that bear mention for sticking valves.

The first is a stuck valve that will not move and that shows diminished or zero compression during a test - your reading shows your engine doesn't have this.

The second might be better termed a "sluggish' valve in that SOME of the time in operation it doesn't move to the fully closed position for each cycle, making the engine run rough. My engine has no thermostat and a completely closed bypass, so it runs relatively cold, and exhibits this symptom very slightly sometimes. I run the bottle-recommended dose of Marvel Mystery Oil in the fuel 100% of the time and it solves the sluggish valve situation 100% of the time. Don Moyer has suggested you can run double the recommended dose without concern. (I think two-stroke outboard oil accomplishes the same thing, with perhaps a little more smoke.)

Maybe this will clear up your situation, and once the valve cycles a few hundred thousand times you won't need the additive any more.

Last edited by tenders; 05-18-2019 at 09:46 AM.
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