Cam Chain / Tensioner Noise

[Mike V]

Need a little help with your experienced wisdom...

Bike is a 1981 R65 unmodified.
Recent full top end job W/ upgraded valves, guides and seats.

I have a very suspicious noise coming from the bike - it resembles excessive valve lash noise but I'm confident that is not the cause.  Brand new top end, valve clearances are good and steady, no axial valve tower lash, rod bearings and wrist-pins are fine when checked during assembly.  The timing chest is about the only thing that wasn't checked during the rebuild. The bike is very quiet when cold but after reaching operating temperature the "clack-tick" starts and is most noticable at idle and seems to be towards the left front side of the engine (peculiar, eh).  At approximately 2000-2200 rpm the noise subsides.  Bike runs strong, responsive and pretty darned near perfect through all ranges.  The last time I had a timing strobe on it the light was steady although I have not checked lately (about 8 months ago).  

A very knowledgeable and reliable local Airhead has put his money on the Cam Chain Tensioner failing.  No formal bet was made...yet.

Has anyone experienced a similar type of engine noise and solved the origin?  Any thoughts ... comments ... questions?  I hate to tear into this thing after totally restoring it, I'm really enjoying riding it.

-Mike V. / San Diego

[Rob Valdez 79 R65]

Hi Mike,

Do the search engine thing like I told you in an earlier PM.  Use the "match as a phrase" for "cam chain".
"Tensioner" might also provide different results.

I'm afraid you might be correct, but as long as the gears are in good condition it shouldn't be that big of a project.  If your timing light is steady, they and the chain are possibly doing fine.

Stuff rags in the holes in the timing chest so nothing falls into the crankcase.

[Mike V]

Thanks Rob,

I'm doing some research now. I'll try to get a timing light on it tomorrow to see if I get some bounce or not out of it.  Sure wish I would have thought (or known) to dig into it while the motor was on the bench.

Oh well, you know what they say about hind-sight.

Thanks again, I'll report back when the diagnostics are done and the project starts.

-Mike V. / San Diego  

[Crossrodes]

Mike if you are going to check/replace the tensioner and or chain I'd take a really good look at the sprockets to see if they are worn.

[Bob_Roller]

How many miles do you have on the bike  ?

The left front side of the timing case is where the (for lack of a better term) shoe that tensions the cam chain is located .

Do you have a mechnics stethescope to verify the location of the noise ?

[Mike V]

Absolutely Mike.  If I get that far into it, I'll most likely do the whole job.  Weird though, the bike doesn't have that many miles on it (±13k) even though it sat docile for nearly 12 years.

-Mike V

[Mike V]

How many miles do you have on the bike?

The left front side of the timing case is where the (for lack of a better term) shoe that tensions the cam chain is located .

Do you have a mechnics stethescope to verify the location of the noise ?  

Bob,

Looks like we were typing at the same time.  The bike has ±13k miles.  Don't have a stethescope but I do have a long 18" phillips screwdriver as a substitute I can use to try to isolate.  I'll first check the timing light, then poke around with the ear driver while idling to see if I can tell a definite difference in sound...left to right.

Thanks,

-Mike V

[Bob_Roller]

I replaced the timing chain on my '81 R65 when it had around 45,000 miles on it, on advice from no offense meant, 'experts' on airhead bikes  .

There was no appreciable wear on any of the 'consumable' parts in the tensioning the of the timing chain  .

It was water damaged bearings in the transmission causing the noise .

As usual, anything is possible, until you determine it isn't the problem !!!!!

[Mike V]

Bob,

There's wisdom in that response.  I'm by no means; eager to tap into the timing chest.  I think I'll do some diagnostics and observe the noise closely for the time being while I ride it.  As I'm confident it won't go away on it's own, I don't believe I'm putting the bike or myself in any danger by just riding it until I can gather more information or reason to get the wrenches out.

Thanks all.

-Mike V.

[Barry]

Mike

The timing chain issues have already been well covered so I'll throw in a long shot and the only other possibility I can think of.

It's temperature related so could it be that the rocker axial play is a little too tight and the rockers arms are binding once the engine warms up.

[montmil]

Just returned from the "Commie Capital on the Colorado" -often referred to as Austin, Texas... so late to this thread.

Mike, Your racket was just like what was plaguing my '81 R65. Used a Harbor Freight stethoscope to "listen" to the timing case and, whoa, was it ever loud in there.

Both chain guide and tensioner were well worn. The chain itself had worn through the plastic "rub" component of the tensioner which permitted the the chain to clatter against the now exposed metal substrate of the tensioner. The spring inside the tensioner's push tube was "relaxed" and also needed replacement.

Crank and cam gears were like new so did not require replacement. Chain may have been OK but "since I was in there"... Mileage itself is not always a good indicator of timing chain or component wear. Riders that putt-putt all day at low revs actually deprive the cam chain and related components of adequate lubricating oil. There's nothing more than a small copper tube, aimed at the chain, spitting oil for lubrication. Low revs and the oil does not get spat out far enough and in proper volume.

Motobins has a kit for replacement with all gaskets and such. That's what I purchased.

See my Timing Chain Replacement photo essay in our Coppermine gallery. Photos show all.

Monte