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GS1000 knocking noise


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My 1085 GS1000 engine knocks a bit under load. Worse when cold, sounds a bit like a big end, but lighter.

I don't think it's detonation. Its done it for years, (15+, 20,000 miles), various carbs and cams. So it can't be anything too serious.

Someone once said it might be the Wiseco pistons slapping. Anyone ever noticed anything similar? I'm not concerned, just curious.

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Yeah, carbs have been balanced, unbalanced, replaced and rebalanced many times over the years,  makes no difference to this . :)

Didn't think it would be pistons, no logical reason really. 

Its not clutch or alternator rotor/starter clutch either....those have been changed.

Beginning to think it's the crank, but can't be too serious... would have started getting worse by now, surely? O.o

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Yep. Never anything in there.

Also, makes good power, doesn't use much oil, no smoke.

Oh well, will carry on living with it. Might get round to a full rebuild one day and find out! I have a spare head and block here ready, and is probably get another crank to be safe.

One day. ;)

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ok, looking back at the 'funny knock sounds like the crank' things that ive seen,  have you checked the three allen bolts on the starter clutch? the flywheel itself? and as it only shows under load, and as an outsider that doesnt sound like its relevant but ive seen it, how about the rear sprocket carrier wheel bearing? under load it will, grumble like a fucked main bearing  but at a standstill, the back wheel will happily spin noiselessly. i know a guy who swapped a bandit engine thinking the gearbox had gone because of similar symptoms, and it turned out to be the wheel bearing in the sprocket carrier. worth a look.

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Thanks, good points.

Yes, I've replaced the starter clutch and rotor.

It was starting to get a bit 'bangy', so figuring it might be on it's last legs I popped on the rotor/starter clutch from my 1000S (which was stripped down, and I know had a brand new starter clutch 1500 miles ago).

That made no difference. (Not only that, the starter clutch housing wasn't too bad, so I've refitted that on to the 1000S and it's working fine on that for now, maybe not having the 1085 kit is helping).

Also, the bike had a new sprocket carrier bearing a couple of years back, so it isn't that.

Cheers anyway.

The trouble with these engines is the finning makes everything seem to come from the same place; a noisy clutch can seem like the top end. And this noise only occurs under load, so I can't get my head down there with a screwdriver. I get the feeling that SEP did something wrong with the crank when they rebuilt and welded it, after it spun on the dyno.

Now it has a standard tune engine it doesn't need a welded crank so it'll be next winter's job to rebuild the engine with a decent used crank, I think,

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also worth checking whist youre at it that as well as tdc being at tdc, the ignition is times up right too. its only the engraved marks on the timing that set it up, so it could be that even with the timing marks in line, the actual ignition might not be in line. if youre checking tdc with a dti, then check that the ignition is wher it should be, and also that the cams are in time too, have you got slotted sprockets?

 

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  • 2 weeks later...
11 hours ago, Reinhoud said:

Take a big flat head screw driver, put the handle to your ear, and the tip to the engine. You use as a stethoscope, works really well.

I've used that method before, but as I said, it only happens under load, so can't really do that while riding!

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