'78 750 engine noise, with video

[verde]

Sorry for the bad cheesy horror movie style hand held camera work

Listening carefully, anyone know what the hideous metallic noise in the back ground is? It isn't particularly rhythmic, sorta comes in and out.

http://www.youtube.com/watch?v=FGQ0xCRzCJE

Thanks

[Nessism]

Exhaust leak? I trust the valves have been adjusted.

[Ranger]

Check the flanges on the headers and also check the gaskets. Sounds like its coming from between the head at the exhaust and somewhere after the baffel. The rhythmic sound makes me believe it is one of these because it would only occur when the exhaust valves open as the piston moves.

Good day.

[GabrielGoes]

is it the clutch basket? put ur ear as close to the problem as u can, also what is that shock looking thing ?

[verde]

Thank you for that, ranger, but it's the other hideous noise hiding behind the post-baffle one.

Nessism, yes, the valves were all adjusted. Right on the line for one of the intake valves, but all others are spot on.

Head was off and went through the carbs too. If it's the same noise as some of the other threads I've been reading then supposedly a carb sync will help it.

GabrielGoes, I didn't try to pinpoint the noise at the time. First test ride and when I heard that I just snapped the quick video, turned around for home, and shut it down. Can probably squeeze some time in to work on it tuesday and see if I can locate the noise better. Shock looking thing is a shock, imagine that It's a mountain bike rear shock with 750 lb/in spring. Way to stiff to put directly under my arse, so it ended up counter-levered like that with my seat just sorta floating.

Edit: Pic of my floating seat. Still need to finish shaping the foam and wrap it. Will post a build thread some time.

[GabrielGoes]

talk about just two wheels and motor!!! that is one very unique design, i can see some 78' 750 in there nice tires they look like bridgestone spitfire s11's?

[GSexpress]

It's kind of hard to pick a knock out of all the other noise.

But I think I can hear some cam slap. It sounds like a little hammer in there pounding on and anvil. But it's comes and goes and is very irregular in frquency.

That is the cam shaft bouncing from side to side. It doesn't hurt anything. A temorary fix is to put the valve cover plugs (the little half moon shaped rubber pieces) in backward. They stick in far enough to control the cams side movement for a while. they eventually get compressed from the cam hitting it. The noise is actually made in the center of the head where the cam hits on a side surface of the locating ring. If you pull the valve cover off and move the cams side to side you'll see and hear what I'm trying to describe.

[verde]

...nice tires they look like bridgestone spitfire s11's?

I put all that effort into the fab work and you notice the tires from the PO?! Seriously though, thanks for the comments. It is surprising how much '78 750 I kept. Even with hard tailing it I was able to retain the stock foot controls. Front fender stays for now too just 'cause I'm tired of eating my own rooster tail every time I cross a puddle on my other bike. I'll save the details for a build thread.

GSexpress, I think you may have just hit the nail on the head. If that's all it is, that makes me a lot more happy. I would have described it a little like a half rattle/half grinding noise, but in the video it does sound more like a gremlin in there practicing his hammer forming. I'll give a good listen to try and pin point it, then try flipping the half moons just to be sure.

[Flyboy]

Every GS I have ever ridden has had that metalic knocking sound, we could never figure it out, my bike has done it for over 10 years, we, in our ignorance, put it down to crank end float, but since I have been on this board, I know better, thanks to all the advise from the knowlegeble people here.
As has been mentioned, it is probably cam end float, or a noisy clutch basket.
As I said, mine has been doing it since Granny was a pin up, never seemed to do any harm, so I have just left it.
But I will look into it now on the rebuild.

[verde]

Thanks Flyboy, that's even more reassuring. Doing the valves was the furthest I've ever been into an engine on my own. Was hating thinking I did that work just to have something else frag itself from the get go. Have not noticed the same noise in a '79 I have though, but that one has 25K less on the clock.

[verde]

Well, I've definitely got both culprits, noise on at the clutch basket and center of the head(and just a lot of noise). To really get it to show itself, I played with the idle up and down when the noise was particularly bad. Much more open area too, so the exhaust noise isn't drowning it out so much.

http://www.youtube.com/watch?v=Jsn3ePNuO-s