gs550 "knocking" sound

[llama777]

I recently aquired a 1978 GS550... After alot of effort getting the old girl to run, I notice that after the engine has warmed up at idle and is stopped I can hear an annoying mild knocking sound-it is definitely not tappet noise. Aside from this, the engine seemingly performs very well. The noise goes away at running speeds- using a mechanic's stethescope, it seems loudest at the bottom half of the engine on the throttle side (right) towards the front of the bike.

Anybody else have an engine with a similar sound or know what it is? could this be the early signs of bearing failure?

[gearhead13]

My engine rattles so much, besides the valvetrain, I dont know whats what
Part of it I think is the springs on the back of the clutch basket (very common), the rest i dunno.
A knocking rod bearing is very distinctive and I would recognize that right away. Plain main bearing knock is sometimes hard to recognize.
It hits redline and doesnt blow up, so??? I will just run it til I figure out what the rattle is or it blows up

[Zooks]

Welcome to the GSR llama777

Knock, knock who's there?


Now as far as your problem is concerned - does it go "knockity-knockity-plonk" or "knock-knock-plunk" or "knock-bang-grind" or "snap, crackle & pop" ????



Seriously though, you sound like you've got the famed 'GS clutch rattle' to me. Hard to say without actually being there. Find someone local that knows about old bikes if you can. It's a good idea to put your location in your 'profile' because then a local person may be able to help you out.

Good luck.

[Old Colt]

These are noisy engines due to all the roller type bearings in them.
The first question I would bring up is how well are the carbs set, Balancing the carbs makes a big difference in sound of an engine at low speeds. Also if any of the idle circuits are even partially restricted will cause a roughness inducing noise.