update: tore down a bit and found the problem.
see this video, and the tread i linked to in it's description
http://www.youtube.com/watch?v=YENOaYCn-Gk
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6k miles on the bike ... this intermittent knock/rattle sound is driving me nuts.
I'm thinking it is either:
decomp getting loose or going bad
cam chain
or the crank balancer
it's the cam tensioner...put a manual one instead of the original
leggenda58 2 years ago