Weird sound between 4000-4500rpms. Audio/video clip included.

[JohnGS850L]

https://www.youtube.com/watch?v=SpAOd2G6Al4&feature=youtu.be

1981 GS850GL with 42,000 mi. Sound is difficult to localize. The sound persists whether it's in gear or not. Unscrewing the tachometer from the drive end does not eliminate it either so it's not the gauges. Valve clearances range from .04 to .09 but the difference between intake and exhaust for any given cylinder is <.03. Cam chain tensioner just rebuilt with new spring and pushrod sanded down enough to *almost* eliminate the groove warn in from the ball bearing on the end of the adjuster... what else.... no noticeable change in power or performance. What do you think it could be and how critical is it to fix today?

[tom203]

"Cam chain tensioner just rebuilt with new spring and pushrod sanded down enough to *almost* eliminate the groove warn in from"

whats with this almost stuff? Maybe you should just get another tensioner.... Did you reinstall/reset tendioner correctly?

[JohnGS850L]

A new tensioner is expensive and I'm a broke student for one more year so why not just rebuild the old one to get me by. Yes, I installed and reset it correctly.

Do you have reason to believe that the tensioner is the cause of this problem?

[John Park]

Sounds like something loose to me. The usual? The heat shields on the exhaust pipes or perhaps the crossover clamp[s]. Exhaust header bolts [ don't break them!] or maybe some jumble in the cables under the tank.

What did you last do to it? It doesn't sound critical, and the rev range seems to be a typical resonant point - maybe frame resonance.

[tom203]

"Do you have reason to believe that the tensioner is the cause of this problem?"

I'm suspicious of petcocks and tensioners. The tensioner plunger needs to creep out and hold position firmly- a groove in ramp or flat spot on ball could let it vibrate at a certain speed. My hearing stinks so your video does not help me!

[JohnGS850L]

Sounds like something loose to me. The usual? The heat shields on the exhaust pipes or perhaps the crossover clamp[s]. Exhaust header bolts [ don't break them!] or maybe some jumble in the cables under the tank.

What did you last do to it? It doesn't sound critical, and the rev range seems to be a typical resonant point - maybe frame resonance.

I will check all of those things, thanks for the suggestions. I only noticed this problem after I had completed the road trip I bought the bike for and felt comfortable riding spirited since I wouldn't be stranded if things went south. For the first several thousand miles of ownership I never had it over 4k rpm unless I was at freeway speeds where the wind masks the sound. One morning I revved up to 5k in first and noticed it. That was about 1,500 miles ago and the problem doesn't seem to have gotten worse at all. I have two weeks where I don't need it to commute to school so I thought "maybe I ought to fix this".

Thanks for your suggestions. I will try and pinpoint the sound better.

[steve murdoch]

Sounds like something loose to me. The usual? The heat shields on the exhaust pipes or perhaps the crossover clamp[s]. Exhaust header bolts [ don't break them!] or maybe some jumble in the cables under the tank.

What did you last do to it? It doesn't sound critical, and the rev range seems to be a typical resonant point - maybe frame resonance.

With no difference in engine performance i tend to agree with the ideas from John.
Just something vibrating.....tank, headlight, gauges.