GS1000 '78 top end noise when warm

[timon1]

Hello GSResources Forum!

We have been working on a Suzuki GS1000 and it's finally ready to be driven around!
What we've noticed after a drive, was there would be a tapping/flippering noise when the engine is warm. It seems to be coming from the top left of the engine.

The carbs are cleaned/synced, valves have been adjusted, compression is tested, all cilinders have spark, the contact breakers have been set (timing+gap).

We're just not sure what the noice could be when it's warm (and if it's worrisome)! Do you guys have any ideas for things to check or what it could be?
It sounds a bit like a valve, but since they have been adjusted I wouldn't suspect them to be an issue.

Noise when warm: https://youtube.com/shorts/BRmQiqLNqyU

Noise when cooled of a bit: https://youtube.com/shorts/pNREmZnSysM
(You can still hear the sound, just a lot less)

Thanks in advance!

Regards,
Timon

[chuck hahn]

Sounds like an exhaust gasket leak to me. run a lighter flame or cigarette smoke around the pipes. if its leaking youll see it

[Nessism]

Agree with the exhaust leak. Did you install new crush gaskets?

Installing an exhaust can be tricky with these old bikes. It's important to use new crush gaskets, and don't tighten up the header bolts unless the muffler hanger bolts are loose. The idea is to pull the header pipes into the exhaust ports evenly, a little at a time, working across the bank. The entire exhaust system will move backwards when the bolts are tightened, thus the need to tighten the muffler bolts last in the process.

[timon1]

Thanks for your take guys! We had a exhaust leak for sure on cilinder nr2, but we just replaced the gasket for another new one, so I thought that was solved. Probably not then!

The exhaust isn’t original and the flanges not in great shape. Just happy it probably isn’t too bad!

thanks again

[steve murdoch]

How about some pics of the whole bike and the story behind it?

[rphillips]

Just something I've got into before. Pieces of old baked in gaskets can be camouflaged in the back of the exhaust port. Same color and texture as the alum. Be sure "all" is cleaned out good.

[timon1]

Just something I've got into before. Pieces of old baked in gaskets can be camouflaged in the back of the exhaust port. Same color and texture as the alum. Be sure "all" is cleaned out good.

Interesting, I double checked this, but luckily it was clean.

The probleem seems to be the weird spacers the previous owner made. They are a bit crooked and bent, making them turn a bit into the clamp. That way the exhaust doesn't crush the gaskets!

IMG_1930.jpg

[timon1]

How about some pics of the whole bike and the story behind it?

The bike is a '78 GS1000, we're rebuilding for a friend. It was in pretty bad shape when we got it, so we pulled it apart.
After a few years it's finally close to done!

gs1000_osr8694.jpg