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Old 09-05-2009, 09:20 PM
Scotchmo Scotchmo is offline
Motorized Bicycle Elite Member
Join Date: Jun 2009
Location: Los Osos, California
Posts: 217
Default Re: BIG Problem with Front Mount and my Bike :)

Originally Posted by moosinatrix View Post
Also i think alot of the motor mounts i have seen on these engine suck! the U shape in the mount is there for a reason, and taking a 2 bolt mount and reducing it to one is justt asking for trouble. i would get rid of the lower plate and make another plate that has a U Shape identical to the motors' and just get longer bolts and clamp the engine to the frame rather then damage your bike frame and engine with their method.
Exactly! The front motor mount is designed to nest firmly around the down tube. Anything else puts extra stress on the mounting studs. If you do it the right way, the studs will not be ripping out the side of the motor mount. The half round recess in the engine block should be taking all of the side loads. If the motor is wedged down into a properly sized V of the down tube and seat tube, the mounting studs will have negligible horizontal shear stress. I would not use most of the large tube adapters that I have seen. Drilling a hole through the down tube at the point of highest stress will compound the problem. That creates a stress concentration that could eventually result in fatigue and failure of the frame. A steel plate cantilevered off of a single muffler clamp or u-bolt is also a poor solution. Iím not saying that these adaptations canít work, but donít be surprised when there is a failure.
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