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Reducing Engine Vibration

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mstull

R.I.P.
Joined
Jun 23, 2005
Messages
1,263
Location
West Texas
Some of the vibration and re'drive belt wear of most single cylinder engines is the result of the lack of an ignition advance system. The spark is way too advanced at idle, causing rough running, excess vibration, and re'drive belt wear.

If your engine has dual ignition... if you turn one side off, it has the same effect as retarding the ignition... since the charge would take longer to burn. All you'd have to do is adjust the carb's idle to run at the propper speed and mixture, on just one mag.

You'd have to remember to switch off one mag for starting and low RPM running. That would include most taxiing and descending. If you forget, nothing terrible would happen. It would just idle faster. But by remembering, you'd save a lot of belt and pulley wear... and reduce low RPM vibration.

You'd also have to remember to turn on the second mag when you apply power for take off. But again, nothing terrible would happen if you forget. You'd just have a more gradual climb.

This technique should work for all engines with dual ignition, that don't have spark advancing CDIs... like the Hirth F-33. If you're not sure if your CDIs have spark advance, it's usually in the engine specs. All current Rotax engines have spark advance... and a nice, smooth idle.
 
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