CB400f - funny engine noise, and a cam chain adjustment problem

[jameseh]

(This is a duplicate of my post on forums.sohc4.net - apologies if you've seen it already)

My CB400F has a characteristic engine noise. With the engine warmed up it emits quite a loud, musical screeching - but only in a surprisingly narrow rev band around 3000 rpm. At 4000 rpm and above it runs smoothly and normally, with a reasonable amount of power given the age of the engine. The tick-over is also pretty smooth, with no obviously excessive chain noise evident. Also, no noise to speak of when the engine is cold. It

[matthewmosse]

Hi, don't want to be an alarmist, but check oil supply to top end. I had similar sounds and symptons from a cb550 and it turned out to be an oil starved top end due to partial blockage of one of the oilways. I'm afraid I'm not familiar with the tensioner on the 400/4 though.

[jameseh]

Thanks for the warning Matthew! I had better keep this in mind, though thinking about that noise, the cam chain remains my prime suspect. Anyway, I am going to let my local bike shop take a look at it.

Cheers
James