Crank balancing

[Mozenrath]

I keep hearing about balancing the crank, but I haven't found any good instructions on how to do this with a china girl. Supposedly it's supposed to reduce vibration and prolong engine life? Can anybody tell me how to do this?

 

[GearNut]

Read this thread for a discussion on this subject.
http://motorbicycling.com/f4/china-girl-motor-build-34287.html

For more detailed DIY info, a web search would be an excellent start. There is much more to it than what a sane person would want to type into a forum thread.
All single crank pin, full circle flywheels are balanced using the same basic procedures.

 

[biknut]

I keep hearing about balancing the crank, but I haven't found any good instructions on how to do this with a china girl. Supposedly it's supposed to reduce vibration and prolong engine life? Can anybody tell me how to do this?

I'm looking into getting a china girl crank balanced now. I'm considering possibilities as we speak.

I think the advantage is a smoother running motor, but probably the main advantage is being able to avoid a really badly balanced motor. I'm thinking the quality of balance of a typical china girl crankshaft is so inconsistent that you're lucky if 1 out of 4 is close, and that's probably optimistic.

This youtube shows a crank someone did a static balance on. I think it's similar to a china girl crank.



Static crank balance - YouTube