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U.S. 41cc Vibration Reduction

Old 11-07-2017, 08:59 PM
Red Baron Mike
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Default U.S. 41cc Vibration Reduction

Could use some help guys!I recently purchased a near new U.S. 41cc that I am now breaking in. I am very pleased with its running, but I am trying to reduce vibration as much as possible. I checked the run-out on the prop hub, it is .006" total run-out. Apparently the threaded hole drilled through the hub .006" off-center. Is this enough to experience a vibration or is this insignificant?

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Old 11-08-2017, 05:54 AM
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It doesen't help vibration at all
Old 11-08-2017, 11:09 AM
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Your abilities sound very good. So remove the hub and balance it.

I would never go too far on a single cylinder engine. There is a point where the only solution is a multi cylinder.

Old 11-08-2017, 11:18 AM
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And .... the small Quadra / US engines were noted for vibration. These were low cost, industrial / lawn equipment engines not really designed for low vibration.
Old 11-17-2017, 10:05 AM
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Yes, I try to keep any prop hub deviation/runout to less than .001", though that is my personal goal and a bit tight.

Also, I just won't have the time to search for it, but there was a good set of posts about balancing engines and I have used the technique to obtain excellent results. Try a search in both this and the "Engine Conversion" forums. The engines like yours were quite often re-balanced by users back in the day...


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