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Motorcycle Discussions => British Bikes => Topic started by: johnnyboy-wonder57 on October 27, 2011, 04:04:09 PM

Title: British twins & vibration, smoothing them out!
Post by: johnnyboy-wonder57 on October 27, 2011, 04:04:09 PM

Interesting article here, about changing the degree of crank pin location, to provide a relatively inexpensive  cure our industries big parallel twins!
http://www.xs650.org.au/smoothness.htm

Cheers

John


JBW

Title: Re: British twins & vibration, smoothing them out!
Post by: R on October 28, 2011, 12:37:25 AM

There are of course quite a few of those 76 degree cranks now around for various engines, and a few 90 degree ones.
A Norton owner with the 76 degree crank said it was smoother down lower, but vibrated like a rough 4 up higher. = fail.
Back to 360 degrees. (Lighter pistons make a difference).

The sidecar boys reportedly love them, more jump out of the corners.

P.S. Twisting a cam to suit must be interesting...