"Ringing" Sound at High RPM ???

My '82 KZ650 CSR engine is quiet at idle and under all normal useage. But when I let her rip, such as around 8,000 to 9,000 RPM - Occasionally - I hear this ringing sound for a brief moment. The frequency is quite high - much more than the engine RPM. I first noticed this between shifts, but have also heard it when in gear, usually in the lower gears.

I have the original cam chain tensioner, and believe it is an automatic type, but I am not sure. I took the unit off some time ago and found it to have two pins that have diagonal cut ends that slide together, plus a spring. I cleaned and lubricated everything, since the parts seemed a little stuck together after 26 years. My theory is, that at high RPM, the tensioner cannot offer enough pressure to hold the chain tight, and the chain touches something inside the engine housing and makes the noise. I have not dismantled anything yet.

Has anyone experienced a sound like this? Do you think I am on the right track about the cam chain and tensioner? If so, what remedy do you recommend? Thanks.

I dont know if this will help but my bike has a similar high pitch sound that I tracked it down to be my front brake lever vibrating. At the high rpms if i put my pinkie finger on the lever it stops. I hope this is your case and not motor problems.

I wish it were something simple like this, but it is definitely coming from the engine. Sounds like someone touched a spinning skill saw blade with a metal tool like a screw driver.

I have chosen to avoid high revs for a while. Kinda like the guy who goes to a doctor and tells him that it hurts when he bends his arm a certain way. He asks the doctor what can be done to keep it from hurting, and the doctor tells him to not bend it that way.

Any ideas???

WABBMW wrote:

I wish it were something simple like this, but it is definitely coming from the engine. Sounds like someone touched a spinning skill saw blade with a metal tool like a screw driver.

I have chosen to avoid high revs for a while. Kinda like the guy who goes to a doctor and tells him that it hurts when he bends his arm a certain way. He asks the doctor what can be done to keep it from hurting, and the doctor tells him to not bend it that way.

Any ideas???

Bill,
in my humble opinion it sounds like a cam chain noise from what you have described...i am not a pro by any means, but thats what it sounds like....the first thing i would do is replace that auto tensioner with an APE manual one if they have an application for your bike...
i would also pull the valve cover and inspect underneath
and look for scuffage to verify ...a good look around with the valve cover off would nt hurt either....good luck and i hope you find the problem.......keith

keith1 wrote:

WABBMW wrote:

I wish it were something simple like this, but it is definitely coming from the engine. Sounds like someone touched a spinning skill saw blade with a metal tool like a screw driver.

I have chosen to avoid high revs for a while. Kinda like the guy who goes to a doctor and tells him that it hurts when he bends his arm a certain way. He asks the doctor what can be done to keep it from hurting, and the doctor tells him to not bend it that way.

Any ideas???

Bill,
in my humble opinion it sounds like a cam chain noise from what you have described...i am not a pro by any means, but thats what it sounds like....the first thing i would do is replace that auto tensioner with an APE manual one if they have an application for your bike...
i would also pull the valve cover and inspect underneath
and look for scuffage to verify ...a good look around with the valve cover off would nt hurt either....good luck and i hope you find the problem.......keith

+1 I concur.

You sure it's not the top timing chain idler gear whizzing?

Oil pressure good?

Example in my build, I have all new Liska timing components. I just recently switched over to synthetic oil and all is smooth at low RPM's...

While on the first ride at 6500 or so, I can hear this high pitch whizzzing sound. Mind you, this is loud enough to hear over my Kerker! :blink: So of course I pull over, listen, twist the throttle nada... On the road again, higher rpm & it's back... Hmmm.... :huh:

Get home, get out the stethoscope, start her up and rev till 5-6Krpm, and followed the sound to the top idler...

Now I had just been in the head within a couple weeks for my valve clearances and it didn't make that sound with Dyno oil... Conclusion was that the synthetic is such a smooth/lick lubricant the top idler was just a spinning and singing away being properly lubed up.... :woohoo: The oil was flowing more freely.

Get yourself a stethoscope and track it down...

If your truly worried about it, as Keith mentioned, just to be sure, open up the top (valve cover) to insure no metal shavings and such in the head/camshaft galley.

While you in there, check your shim clearances.

Good luck in tracking it down...

OMR

As a follow-up regarding the high RPM "ringing" sound, my problem has been solved !!!

keith1 and Otakar were correct. I replaced the automatic cam chain tensioner with a manual one. I believe that at high RPM, the centrifugal force of the chain slinging outward - would overpower the spring in the automatic tensioner and allow slack to form.

I looked from both top and bottom of the engine and could not see anywhere that looked scuffed by the chain. Anyway, all is quiet now.

WABBMW wrote:

As a follow-up regarding the high RPM "ringing" sound, my problem has been solved !!!

keith1 and Otakar were correct. I replaced the automatic cam chain tensioner with a manual one. I believe that at high RPM, the centrifugal force of the chain slinging outward - would overpower the spring in the automatic tensioner and allow slack to form.

I looked from both top and bottom of the engine and could not see anywhere that looked scuffed by the chain. Anyway, all is quiet now.

Quiet is not good. Quiet means that it is not running. Fire the bad boy up and make some noise. :woohoo:

WABBMW wrote:

As a follow-up regarding the high RPM "ringing" sound, my problem has been solved !!!

keith1 and Otakar were correct. I replaced the automatic cam chain tensioner with a manual one. I believe that at high RPM, the centrifugal force of the chain slinging outward - would overpower the spring in the automatic tensioner and allow slack to form.

I looked from both top and bottom of the engine and could not see anywhere that looked scuffed by the chain. Anyway, all is quiet now.

Sweet!!!