SOHC.co.uk Forums > CB350/400

400 F2 Noise

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cliff7:
I  wonder if anyone can help identifying a noise on my bike. I have had the clutch apart and everything seems in order (to me) and clutch rubbers seem to have been replaced with no obvious back and forth play.
https://youtu.be/87jPjI33DMw
Engine was supposedly rebuilt not too many miles ago. Don't know whether I have done the YouTube link right.

K2-K6:
Certainly it doesn't sound as refined as it should, the sound of the engine will be amplified through the transmission and with the clutch pulled that's normal to hear less noise.

More to the point is why it's noisy in the first place.  Rebuild can mean such a different level of internal condition on these engines with no real easy way to diagnose, certainly from a remote look most view is speculation or guesswork. 

Initially it would be wise to verify general service items, tappets, ignition setup, carb sync, cam chain tension etc to make sure it's not contributing to the sound.

The immediate suspects for inspection are the cam chain tensioner and if that's working as it should,  then looking with the sump removed to see what level of wear exists in the primary drive chain. With any significant wear in either chain then you'd not expect it to run smoothly.

Nurse Julie:
It's so difficult to tell from a phone vid but it doesn't sound right. How long ago in miles and time was the engine rebuilt, what did the rebuild consist of? What does it sound like when you rev her up?. Are you 100% sure the clutch rubbers have been changed? It sounds very 'top end' are the tappets adjusted correctly?

cliff7:
Many thanks for replies. Previous owner had it for about 2 years but hardly used it. Owner before him passed on loads of invoices and notes but not a proper diary. it goes quieter when revved. Clutch rubbers have screws holding them rather than rivets and I can't get any movement by hand. Tappets have been done and checked again. Timing seems spot on. Horseshoe is free as a rod down blanking screw hole moves up when rotating engine backwards. Had sump off but not sure how to check primary chain. Oil light goes out immediately on start up. Wish I lived closer to those that might know. Thanks again. Oh, and noise doesn't seem louder with dipstick removed.

hairygit:
When were the carbs last balanced, out of sync carbs are the biggest cause of bottom end clatters on these old SOHCs

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