GS engine noise.

[Oldtimer550]

I have 1978 GS 500e 4 cylinder Italian import same as GS 550e

Been tinkering with it for 18months to get running right. It had previously been stood for a couple of years. Replaced reg/rectifier, carb clean rebuild, dynatec ignition, valve clearances done, usual oil filter etc.

Runs lovely now, but I’m getting some engine noise, starts ok and sounds ok, when I accelerate off I get what sounds like a whirring/dry bearing noise, it doesn’t get any louder when I accelerate, if I pull in the clutch it doesn’t change anything. When I come to a junction slow down to around 10 / 15mph it abruptly stops until I accelerate off and it starts again.

I loosened the cam chain adjuster and let it reset that didn’t seem to make any difference. I don’t think it’s the cam chain because I can make out the separate whirring of that. I’ve had three runs out so far covering around 70 miles and doesn’t seem to have got any better or worse.

Can anyone help. Don’t want to keep running it and cause major damage.

[rphillips]

A few yrs. back, my Honda CB1100F would start whirring when the speed got up a little, later on the speedo quit working and the whirring did too... No clue about your problem, but takes only a minute to disconnect cable to assure that's not it.

[steve murdoch]

Even if you think you can pinpoint the whirring sound of the cam chain could the sound possibly be the infamous GS "cam-walk" sound?
Clacking, whirring sound?

https://www.youtube.com/watch?v=wBAckwkiWi4

[Oldtimer550]

You could be onto something with the speedo cable I did have it disconnected when I did the shims. Will disconnect and give it a run. Just checked the video on cam walk I don’t think it’s that it’s only at higher revs and stops abruptly when the revs drop. I was wondering if it was a bearing somewhere a when the revs build up the oil pressure drops and the noise starts then as the revs come down there’s more oil pressure so more oil in the bearings hence no noise.
Please tell me if I’m wrong. It’s only a guess as I’m no expert just learning along the way.
I’ll try get a video of it happening and post. Thanks for your help so far.

[rphillips]

Doesn't sound right at all, to me., The faster the eng. turns, the faster the oil pump turns, the faster the oil pump turns the more oil it pumps. Oh sorry I forgot yesterday, ,, "WELCOME"

[Oldtimer550]

Ok thanks that sorts that idea then. Could it be something to do with the oil pump? Do the go wrong ? The bike had been stood a few years before I got it.

[rphillips]

From what I've seen, oil problems on a GS are pretty dang rare. You say "If I pull the clutch it doesn't change anything". To me that points to wheels, chain, or speedometer turning, everything else slows when clutch is in.

[Oldtimer550]

Definitely sounds to be coming from the engine.

[rphillips]

I dun'no...Appx. what speed does noise start and stop?

[Oldtimer550]

Starts when I’m approx 100 yards setting off from home so probably 15 to 20mph, then stops sharply when I’m slowing down approaching a junction etc so around 10 to 12 mph. Didn’t have chance to get out tonight, but started the bike up and build up the revs and went through the gears while on centre stand and didn’t hear anything. Going to do a road test later in the week and try and get a recording.

[dgates1]

I'd say if it doesn't do it on the center stand, then look at the front wheel. Speedo like previously mentioned seems likely. Maybe wheel bearing.

[Oldtimer550]

Yes thank you that idea makes more sense now will check out.

[Carter Turk]

Could be a loose starter clutch (SC) attached to the rotor. I've had my fair share of issues there.

Not sure if a 500 has a copper plate inside the SC, but might cause a viby sound if loose.

I'd get a proper rotor puller & gasket beforehand & rule out the other suggestions first.

You can lean the right handlebar against a bench or wall, so the bike is leaning a fair amount & avoid having to change the oil.
Just have a rag handy along the lower frame rail.

[Rich82GS750TZ]

Before spilling any oil or undoing any covers where you may have to replace gaskets, do your self a favor and remove the speedo and tach cables one at a time. Go for a ride and rule those out. It may not be the cables, could be inside the instrument. But if the noise is gone on one of your runs, then you know where to look. I replaced a tach (or was it the speedo.Don't remember) that whirred like you are describing. Oiling the spindle hole helped a bit but not much.

But without a video with sound, we're all just guessing.

[Oldtimer550]

Thank you everyone for your help. It was the speedo cable. All sorted.