Over the years I have owned a few bikes that, due to manufacturing stack-up of tolerances, were poorly balanced and vibrated excessively. The latest is my `95 G-G 160. The last was my `96 Section. Being so sensitive to my hardware, I detest things like unecessary vibration. Just thought I'd pass on a little trick to the list to bring these deviants back to a level of vibration you don't notice when riding.

I remove the magneto cover and place weights on the flywheel any way I can, such as putting nuts onto screws and screwing them into available holes. I ride the bike to see if it gets better or worse as I fiddle with amount and position of the weights. Make sure the weights can't fly off, or you may get hit!

This is an iterative process that requires as much as full day of fiddling. Mark positions on the flywheel and keep a written log of what's better or what's worse. Once I get close, I remove the flywheel and machine the rough equivalent of the weight off on the opposite side. You usually have to machine off weight because there is little room available to add weight. I may go through this process several times until I have a sweet result.

If there is nothing fundamentally wrong with the motor that is causing the vibration, I can usually get good results by shaving 5 to 40 grams here or there. That's not enough to cause a problem with fatigue life of the portion of the crank supporting the flywheel.

I am considering a tool to help find optimum balancing weight and position. Does anyone know if there is one available already that I could adapt? The whole process is currently very unscientific. It works, but any tool that would help would sure speed things up a bunch. I'll play with various concepts when I get around to fiddling with the 160.

This sentence no verb.

Chris (CJ) Johnson
Director of Engineering,
College Park Industries, Inc.
(810) 294-7950 (at CPI), (616) 664-4173 (home office)
papazit "at" juno.com