Noise = Tic-Tic-Tic

[Mike V]

Reluctantly, I start this thread.  Engine noises are as hard to diagnose as they are to explain, at least for me.  But, at some risk I wanted to throw this out to all of you.

My 81 R65 has always made a ticking sound at engine rpm tempo only when warm.  It's dead quiet at start-up and doesn't start until the bike is at operating temperature.  Before we go any further, I don't believe it to be tappet noise.  I've checked rocker tower axial play and valve clearances.  Remember the top end is fresh and new on this bike and the valves are adjusted (004"-.008").  The noise I'm hearing is more "tinny" than typical tappet noise and not dull enough to be rod bearings or wrist pins or in the bottom-end for that matter.  Originally I thought this to be pushrod contact with the end of the pushrod tubes, in fact Oak even posted my story a while back in Airmail after I discovered scoring on the pushrods during the tear-down.  During the rebuild I rotary tooled the ends of the tubes as directed (see attached pictures).  The timing light is dead steady so I've ruled out a worn or sloppy timing chain, bike only has ±11500 original miles on it.  Runs purrrfectly and uses no oil.  I haven't pulled the pushrods since the rebuild, maybe I didn't take enough off the tube ends.  I've heard the same noise on other's 650's.  I just don't think it's something normal, my other airhead doesn't exhibit this noise.  Curious if anyone can lend some opinions or ideas.

-Mike V.

[Bob_Roller]

Have you tried a mechanics stethoscope to try and narrow down the area of the noise ?

[Barry]

Just thinking aloud.

One thing you didn't mention Mike is piston slap. My only previous experience of that was the noise was there from cold and disappeared when warm which I guess is what would be expected as the piston expanded but that was iron cylinder/alloy piston.

Does the same hold true for alloy/alloy ?

[Mike V]

Have you tried a mechanics stethoscope to try and narrow down the area of the noise ?

No, not yet Bob.  Good idea. I have an extra long screwdriver I may poke around with up to my ear.  Almost sounds like it's coming from the left side, but who really knows.  I'll see if I can narrow things down.

Barry, I doubt it's piston slap but the sound is similar to that.  To me; it almost resembles a detonation sound or an ATU unit with a loose weight smacking the cover.

[montmil]

Mike, I had a bean can that was making a "funny sound". Turned out to be the rotating metal shield -has the trigger "window" in it- was bumping the Hall sensor. Small, gentle tweak and the noise went away. My noise was constant from start up to shut down, so it may not be even close to your noise.

Perhaps something in the timing chain case?

Harbor Freight sells a mechanic's stethoscope that r-e-a-l-l-y transmits sound. LOUD ...but a cheap price.

Monte

[Mike V]

Thanks Monte,

The bean can is one area I haven't investigated...but I've been wanting to get into it to service and lube.  I hope this isn't resonating from the timing chest.  I'll do more investigation & elimination when I can.  The sound doesn't occur until the bike is at or near operating temperature.

-M

[montmil]

... The sound doesn't occur until the bike is at or near operating temperature. -M

That's what got me to check, discover and replace a timing chain plus guide and tensioner plus the very important tensioner plunger spring. My spring had collapsed in length and was not providing correct chain tension. Noise did not develop until full ops temps. Plus the chain guides were totally gerfunken.

A sorta PITA to get into the timing chest as the exhaust has to come off.  [smiley=lipsrsealed.gif]

Monte