Intermittant Bottom End Knock

[Anonymous]

My GS450S has a bottom end knock that seems to come and go. It started about two years ago right after it was dropped, when the engine ran for a few seconds with the bike on it's side before I could cut it off. (I'm assuming it didn't get oil for those few seconds). When it does it it seems to do it only at lower rpms, generally below 3500, and it does it in all gears. Sometimes it will go months without making any noise, but it just started again today on my way home from school.

What is the best option for fixing it? Should I just find another 450 and swap engines, or try and rebuild this one? Or should I just keep riding til it blows up?

[flyingace]

I've had a knocking noise in my bike for 2200 miles. There's conclusive evidence it's a rod bearing and conclusive evidence it isn't. You can do the wooden dowel test (see old engine Q&As) to check for rod bearing movement.

I am so frustrated trying to figure out this noise, I decided to keep running the engine just to find out what it is. Let the rod blow out thru the case - at least I will know!

PS - I have a spare engine.

Ace.

[Pete's GS]

It's probably the clutch basket rattling around with age (and looser tolerances) and nothing much to worry about. (Really, its the tabs on the clutch plates growing smaller, creating more play.) Bottom end failures are mighty rare in modern bikes, and certainly so in the over-built GS.

[Anonymous]

The bike only has 6000 miles on it though... could it still be the clutch basket?

[Dink]

A 450 is plain bearing rather than roller like the bigger Gs's so it very likely that it is a rod bearing, keep your eyes open for another motor,as you may eventually need it, you may not though.

Dink