CR500 - Crank Shaft Balance Factor

Discussion in 'Fabrication, Welding, Machining' started by RATRACING, Feb 6, 2006.


    RATRACING Rookie DRN Member

    Feb 6, 2006
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    Fellow Tuners:

    I am looking for the Crankshaft Balance Factor or "bob weight" for a mid 90's Honda CR500 for 8,000 RPM.

    Obviously, I am looking at turning it much faster than stock. It will see brief periods of 8,000 RPM (I know this exceeds safe piston speed limits), but it only goes there for 10 seconds at a time and is rebuilt frequently.

    Any input would be appreciated!


  2. cujet

    cujet Member DRN Member

    Aug 13, 2000
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    The balance factor does not change much for singles. To some extent the BF is chassis related as the mass of the chassis affects what you feel.

    53% is a good place to start for your engine.

    Also, I am sure you are aware that it is total bunk that a single (such as a CR500 engine) can be balanced at a particular RPM. Without some serious engineering tricks such as counter rotating balance shafts or counter rotating crankshafts, the lowly single is going to shake in both X and Y axis. The amplitude of vibration in each axis is what is controlled by the balance factor.

    Edit: I wanted to add that a heavier crankshaft counterweight on a vertical cylinder engine will decrease vertical vibes and increase horiz vibes. There is no free lunch!

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