Thought noise was cam chain, now not so sure

79 KZ650

Have had an intermittent noise I suspected was the cam chain.

Took it to a shop. The guy listened to it and immediately diagnosed it as a cam chain noise. Said he believed the automatic tensioner was bad.

He later told me the tensioner was all gunked up from the oil not having been changed regularly, and all it needed was a good cleaning to correct the problem.

I got the bike back, and the problem was not corrected. I took it back to the shop, he said he could hear the problem was not corrected, and told me he'd get to it the next day.

A week and a half later, after not having any of my calls returned, I went to the shop. He told me he'd ordered a complete tensioner assembly from Kawasaki, and had not recieved it yet. I looked at the bike, and saw the tensioner had not been removed. I asked him how he knew which parts of the assembly were bad if he hadn't looked at it. He had no answer.

I took the bike. We pulled the valve cover, and the chain tensioner. The cam chain is tight and looks good. We can't see anything visibly wrong with the chain tensioner. We reassembled the bike and ran it, using a long screwdriver, and listening along it, to try and isolate the noise. It is loudest on the upper side of the engine case, away from the cylinder; closer to the starter. I'm wondering if what we're hearing is even the cam chain at all.

The noise sounds exactly like something like a chain making light contact with the case or other soft, or round metal; it's not a grinding sound, more like a rubbing sound.

Does anyone have any ideas?

Post edited by: seanof30306, at: 2007/09/29 08:36

Loudest at idle, goes away when you rev up the motor?

If so, that's a characteristic of primary chain noise, and it's right where you are hearing it.

Pretty common complaint, and normally if you sync the carbs it gets quieter.

Of course it could be something else, it's pretty hard to diagnose a noise over the net

Post edited by: steell, at: 2007/09/28 23:59

steell wrote:

Loudest at idle, goes away when you rev up the motor?

If so, that's a characteristic of primary chain noise, and it's right where you are hearing it.

Pretty common complaint, and normally if you sync the carbs it gets quieter.

Of course it could be something else, it's pretty hard to diagnose a noise over the net <br><br>Post edited by: steell, at: 2007/09/28 23:59

Thanks for responding.

Yes, it's loudest at idle, and yes, it goes away when the motor is revving up, but, you hear it start when the motor is settling back down after revving up.

When you say "primary chain", do you mean the drive chain?

No, the primary chain is a HyVo type chain that connects the crankshaft to the secondary shaft, which then drives the clutch.

It's #6 in the pic below

And in this pic you can see the gear on the crank that drives the chain, it's just left of center.







The parts diagrams at kawasaki.com "really" help

Post edited by: steell, at: 2007/09/29 08:24

Man, thanks for all your help.

Now, how serious is it when the primary chain is making this noise? If it's still doing it after we get the carbs right, is there an adjuster? I don't see one in the diagram.

It doesn't hurt anything, I don't believe, when it's noisy. There is no tensioner, the chain just eventually stretches and as mentioned will rattle to beat hell if the carbs are not synced. replacing the chain means removing the engine, splitting the cases and removing the crankshaft. Not an afternoon project or something you want a shop to do at $70 an hour I wouldn't think. If it's that I'd leave it be. How many miles do you have? I went the entire 162,000 on my original KZ650 engine without replacing the chain and I'll admit it was rattling a little :laugh:

IIRC, (haven't looked it up recently) the service limit on the primary chain is 25mm (close enough to 1") of up and down travel between the two shafts (crank and secondary).

It will make a lot of noise long before it gets to that point.

Sync the carbs and it will probably be a lot quieter.

A new chain is near $200, plus the labor to install it.

Post edited by: steell, at: 2007/09/29 14:20

mileage is 28,600 ish. i assume this noise at idle will also be heard when starting?
please bear with me. im new to cycles.
but have 30+yrs with automotive. dealing with the carbs. after rebuilding the carbs is there a standard adjustment on all the jets? ie. turned all the way in and 2.5 turns out. like on a rochester quadrajet?
next question, what manual would be recommended to properly tune a bike. just until i get more comfy with knowing what to listen for?

thanks jim.

jccwall wrote:

mileage is 28,600 ish. i assume this noise at idle will also be heard when starting?
please bear with me. im new to cycles.
but have 30+yrs with automotive. dealing with the carbs. after rebuilding the carbs is there a standard adjustment on all the jets? ie. turned all the way in and 2.5 turns out. like on a rochester quadrajet?
next question, what manual would be recommended to properly tune a bike. just until i get more comfy with knowing what to listen for?

thanks jim.

FYI

Jim is the guy working on my bike.

steell, do you have a parts page for the carbs?

on the right side of the page there is the "The Essentials" list. Find the one that says Kawasaki Parts Diagrams... on e you go there just find your model and you are set.

All the pictures you could want!