Noise from transmission

[Guest]

Hey everyone, just this past couple of weeks I've noticed a new noise coming from the transmission case. It only occurs while in gear, and decelerating, so I can't recreate it in my garage for you. When I let off the throttle, I get repeating "clunk...clunk...clunk" about 2 clunks per second. It sounds like metal-on-metal, so I believe it's transmission related- any clunking that loud in the motor would certainly cause something catastrophic, and the bike runs smooth at all others times.

Think it's just something loose in the gear/clutch assembly, like I've read is common? Each time I hear it, I wince a little.

Bike is an 80 GS1000E, about 30k miles.

[tom203]

"When I let off the throttle, I get repeating "clunk...clunk...clunk" about 2 clunks per second. It sounds like metal-on-metal,"

make sure your drivechain is OK. Will it clunk,clunk in neutral?

[roeme]

My bike made this sound when the front sprocket became loose, and when both chain and sprocket teeth (front and back) were worn out enough (I did first suspect chain slack).

Check if this applies to you. Do it ASAP, taking off the sprocket cover takes 10 minutes at most.

Should it be the case, all you need at most is a chain/sprockets kit. If the sprockets and chain are still good, you'll just need to tighten the front sprocket to spec. Easy fix.

Edit: And yes; mine didn't make the sound in neutral as well, and only under certain loads (slight or no pull/push load, and change in between).

[JamesWhut?]

Yup. Sounds like chain tension is slack and/or worn out sprockets.

[StratJeff]

Great, I'll start there and let you know what I find.

[StratJeff]

Well I did the easy thing first- tightened the chain tensioner bolts on both sides by 1 notch, and the noise is gone! No clunk on deceleration at all.

However, I did notice the chain contacting the center stand, and some wear on the stand. Certainly this isn't normal, right? Just another symptom of a slack chain? Cheers all.

[sealpup]

That chain looks like it needs a really good clean, then plenty of lube.

[hillsy]

You should also make sure you have your chain tensioned properly. Tightening it by a notch at the swingarm might actually make it too tight.

[roeme]

Would you take a picture of the sprocket teeth for us?

And yes, the chain shouldn't contact the center stand, at all.

Since you've run the chain with so much slack for a period, I dare say that your chain is worn. Usually some links are lengthened too much, no longer matching the sprocket teeth distance.
Whenever these lengthened links (one or more) enter/leave the sprocket, one gets the "clunk!".

Sprockets and chains wear out each other, any of those out of spec, or slack, fastens the process.

I think it's safe to order a chain/sprocket kit now, and checking both chain and sprockets now, to decide when to change them out. You will have to at some point in the near future.

Who's willing to take bets how many km's it will take until the clunk returns?

Don't ignore the signs your bike is giving you. Above doesn't cost much, and doesn't take much time.