What sound does an early failing crankshaft bearing maike/

[Peter#1266]

Hi all, I have an 82 GS1100GK.Purchased used about 30 years ago with about 40,000km on the clock, used regularly till about 2008 when I got a new bike (KLR650), Been stored in a dry shed since, oil down the cylinders, carbs and tank drained, oily rags in the exhaust ports that were then plugged with plastic plumbing pipe caps (perfect fit!). Recently decided to resurrect the old beast, and did all the usual things, new engine oil, filter, spark plugs, new oil in transfer and final drive, new tyres, new brake pads, caliper rebuilds, carbs cleaned, new air filter, new cam chain, valve grind and clearances. And with a tank of fresh gas it fired tight up. BUT - there is a quite loud knocking noise from the engine that is most pronounced at idle , seems to go at about 2000 plus revs. I suspected the clutch basket springs, pulled the basket out and yes all 6 springs were loose. Another basket installed and the noise remains.
I guess this is a long winded way of asking - what does it sound like when ether a main or rod bearing is starting to fail?

TIA
Peter

 

[chuck hahn]

I didnt see carbs synced mentioned. How about the clutch basket bearings? Starter clutch bolts tight? It goes away around 2000 rpm you say?

 

[GregT]

Check the valve clearances. OHC engines like the GS and old jaguars have a nasty habit of seizing a valve or two while sitting for long periods.
When they get turned over, a valve can get bent. It'll still open and close but the clearances will have become much bigger.
Typically, the noise does go away as the revs rise.

 

[Peter#1266]

Carbs mechanically synced, dont have vac gauges yet. Clutch basket bearing 'felt" ok but I am going to confirm that by removing the entire clutch and running the engine (cover back on obviously) . Starter clutch was one of the first things I looked at. The noise does seem to go away over 2k but maybe its just getting lost in the overall sound. Its got a quiet muffler (Bandit 1200 can on a 4-into-1 . Will also look closer into the cam end float

 

[TeamDar]

Carbs mechanically synced, dont have vac gauges yet. Clutch basket bearing 'felt" ok but I am going to confirm that by removing the entire clutch and running the engine (cover back on obviously) . Starter clutch was one of the first things I looked at. The noise does seem to go away over 2k but maybe its just getting lost in the overall sound. Its got a quiet muffler (Bandit 1200 can on a 4-into-1 . Will also look closer into the cam end float

Do not run the engine without the clutch assembly. The oil pump requires the clutch basket to drive the oil pump gears.

 

[Gorminrider]

Are these "shim" valves? Symptom sounds similar to "cam walk" which is harmless

 

[bwringer]

Do not run the engine without the clutch assembly. The oil pump requires the clutch basket to drive the oil pump gears.

Agreed! Do NOT do this! Besides, you won't learn anything useful.




Sitting here on the other side of the internet, it sounds like the carbs aren't synced. A mechanical sync is only just barely good enough to start the engine. Unsynced carbs can create some very alarming noises, since each cylinder is sort of doing its own thing. My bet would be that it'll get better when you do a proper vacuum sync.

A bad crank or rod bearing on a roller bearing engine is EXTREMELY unusual, and unless you stored the bike in a pond, I can't think of a way it could happen from storage. If that's what it was, it would get louder when you rev the engine, and louder yet when you put a load on it.

Cam walk is harmless but can make some gawdawful noises as well, but I don't remember that it affected the 1100G/GK models much. Again, it wouldn't suddenly appear after storage.

Accidentally leaving the vacuum line off #2 can make things noisy, too, since #2 is sort of coasting.



When you hear hoofbeats, think horses, not zebras.

 

[Peter#1266]

Thanks for the answers / suggestions.

Good point about the oil pump I hadn't considered that. The intention of running it without the clutch was to eliminate the transmission as the source of noise. The noise is still present when the clutch is disengaged, trans is in gear and rear wheel locked (when on the centre stand) so nothing in there spinning except the clutch basket, so I guess this achieves more or less the same result
Vacuum line to gas tap is installed correctly. It runs on all four at idle and up, idle speed is about 1200 and is pretty smooth, just noisy
No valves stuck open. I had the head off to replace the cam chain so did a quick valve grind / new seals and did the clearances while the head was on the bench. All are in spec, with one or two at the high end (but not exceeding) the spec.
I also forgot to mention in the initial post that new intake manifold/stubs and O rings have been fitted.
What is everyones preferred brand of vacuum gauge setup?

(bwringer = my KLR is also a 685. Wakes them up a bit, doesn't it)

 

[timebombprod]

Carbtune pro

 

[chris]

Hi, I agree with Bwinger. Doubt it is roller bearings. You can try to wiggle the crank ends to see if you got play. Are you sure it's not the cam chain slapping. That would explain the noise going away when you rev it. You can turn the tensioner to see if the sound changes. Just my thoughts

 

[Guest]

My '83 GS1100e recently had what turned out to be a failing main brng, the noise was a cyclical whirring/clatter I posted a you tube video of the noise a couple times before I finally tore it down. Now to find a decent crankshaft, or rebuild mine to the tune of 1,000 bucks or more...my main brng noise didn't go away with revs just got faster...

 

[timebombprod]

My '83 GS1100e recently had what turned out to be a failing main brng, the noise was a cyclical whirring/clatter I posted a you tube video of the noise a couple times before I finally tore it down. Now to find a decent crankshaft, or rebuild mine to the tune of 1,000 bucks or more...my main brng noise didn't go away with revs just got faster...

Can you link the videos?

 

[1948man]

https://www.thegsresources.com/_for...e-noise-has-me-rattled&highlight=main+bearing