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Old 02-10-2011, 06:20 PM
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2door 2door is offline
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Join Date: Sep 2008
Location: Littleton, Colorado
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Default Re: Glad I found you!

Quote: (I bet it really cancels out some vibration.)

This idea has been discussed here many times before. Mounting an engine in rubber will not eliminate or cancel out vibration. What it does is, as I said above, transfer the vibration to the fasteners, which will eventually fail. You can not compare the mounting system on our little two stoke engines to a motorcycle or car, both of which use resilient mounts. By virtue of the mount design of the engine they rely on a solid, full contact approach which will cause some vibration in the bike frame.
Soft mounting the engine does not address the source of the vibration, which is the engine itself. Isolating the vibrations to the engine means that the fasteners (studs and nuts) and even the engine case then must carry the brunt of those vibrations, a task they were never designed to do. They will fail. Over tightening them, using thread locking compounds, nylon lock nuts, lock washers or any other method will not remove the stress put on them by soft mounting the engine. This is not just my opinion by the way, it is a mechanical engineering fact that can not be ignored.

Soft, or resilient mounts used in cars and motorcycles are a two sided affair whereby there is rubber or a reslient material between the engine case (block) its fasteners and the frame in which is is mounted. Take a close look at any automotive or industrial engine mount and you'll see a metal-rubber-metal sandwich, not just rubber on one side. If one was to experiment with this type of mount they might find a noticable decrease in the vibrations transmitted to the frame but you will still have to deal with the remaining parts of the engine and those that are connected to it in the way of vibration effects.

I'm not interested in blowing my own horn here; what I want to see is a new comer to the hobby enjoying his bike without the frustrations that will surely come from another unsuccessful attempt to soft mount the engine. Every successful and experienced builder here will agree with me on this. Mount the engine as solid as you can get it and enjoy your bike.
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