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Primary chain noise

Submitted by john_crocker on Fri, 16/08/2024
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Light Twins

Is this a thing with lightweights?
I can hear the primary chain "walking" around the sprockets.   Most noticeable at 30 - 35 mph in top gear.
I've replaced the part worn chain with new from the club, crank shaft sprocket is new and clutch sprocket is in good shape.   
The new chain has made a noticeable difference to the noise level, much quieter but noise is still there.  
Anyone else have this noise?

Submitted by john_crocker on Fri, 16/08/2024

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...mentioned that the chain is tensioned as specified in the manual.

To clarity what I mean by the chain "walking" around the sprocket is that due to the combinations of teeth and link numbers, its quite a few rotations of the crank before the a combination of teeth/links meet up again.

It can be heard as a noise related to engine speed but not at engine speed. Only seems to manifest itself at the speed I mentioned, other speed the engine sounds good.

Submitted by peter_holland1 on Sat, 17/08/2024

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Never heard the noise you mention John. In my experience the lightweight is at its quietest when just rebuilt with new bearings, warmed up, and oil still cold. It still sounds rather rattly to the faint hearted. The exhaust noise from the ineffective silencers hides most of this shortcoming very well once on the go. Adding a well fitting helmet and earplugs should enable owners of a nervous mechanical disposition to attain broad smile factor and to wind it up to at least 30 in 2nd and 40 in 3rd before changing gear.
Properly rebuilt like yours, they can give a lot of pleasure. 
Peter

Submitted by john_crocker on Sat, 17/08/2024

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Paul, Sprockets run true and are aligned. With the new chain, tension is constant at any position.
Peter, you flatter me! I would like to think that I have rebuilt the engine properly but what I have done is heavily modify the engine. A little over 500 miles so far and it hasn't gone bang, yet.
The chain noise is annoying, I would like to think its because the engine is so mechanically quite that noises usually drowned out are now audible. If only!!!!!

 



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