From:Perry Ruiter Electronic:perry -A- ruiter.ca
Subject:RE: RE: RE: Flywheel plates? necessary or not? Date:Fri Jul 30 20:42:40 2010
Response to:14090
I learned a long time ago for all round use it's hard to beat stock. Harley (and DKW before them) had smart people determine what was the optimal mass for the flywheels. I don't think I can do better by pouring some melted wheel weights into the crevices. A good automotive machine shop should be able to balance it, but you may need to take the flywheel assembly apart, remove the rod and put it back together to have it dynamically balanced (and then take it apart and put the rod back in and reassemble it for use). Long and the short of it - it's probably cheaper to find a replacement stock bottom end ... Perry

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Perry,

Thanks for a great response, very informative. It raises a couple of other questions.

1. A heavier flywheel means slower revving, but higher torque. Higher torque on a small displacement engine like this is desirable, I would think , but will the greater inertia do harm to this little single?

2. Where can I take this crank to check it's balance? Is that standard equipment in any engine shop, or do I need to find a shop with a machine devoted to motorcycle cranks?

Thanks,

Joe

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They serve to raise the compression in much the same way as a stuffer plate does that the racers use. The photo of the flywheel shown isn't just missing its plate, it looks like the void has been filled with lead(?). This would have the same effect has the plate (while playing havoc with the balancing if not accounted for). Attached is a photo showing an unmodified flywheel without it's plate ... Perry

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When I split the cases on my '52 125S, I noticed that there were no flywheel plates (23730-47) flywheel. I got to wondering if they actually serve a useful purpose, or are they just to hide the ugly face of the flywheels (see pic)? I would appreciate a discussion of this among the older hands. Thanks.

Joe