Cam Chain Stretch?

Hey Guys,
Bike project was sitting on hold for a year or so, but into some free time again.

Here is where i stand... I am putting my cams back into bike (which i have done before) Re-timing, ensuring that there are 36 pins between each mark on the camshafts, as per the manual.

Everything lines up perfectly just as it should. I release the cam chain tensioner, then using a wrench turn the engine over a few times, and back to TDC1.4. At this point the timing alignment mark on the inlet side of the engine is approximately 3-4mm below the mating surface of the valve cover. I am assuming that this is due to stretch in the timing chain. I think that i just never noticed it previously, because i never spun the crank after setting everything up. The exhaust cam lines up properly still.





I measured the cam chain with a caliper, and it seems that it is at least close to within spec.

Is this something to be worried about? I repeated the process multiple times, and i can assure you i have set things up correctly as per the FSM.

Is this just a regular wear thing? anyone else ever run into this?

Thanks
Andrew

1977 kz650 C1

How many miles on the bike?
Steve

the engine is a replacement. Previous owner said it had around 40000km, but i cant be sure....

If you performed the pin to pin check and didn't find the chain over length then I wouldn't worry any further.

You stated " I release the cam chain tensioner". Did you then adjust the tensioner according to the manual before measuring the cam chain position? Ed

650ed wrote: You stated " I release the cam chain tensioner". Did you then adjust the tensioner according to the manual before measuring the cam chain position? Ed

Thats right. I aligned the camshafts, tightened down the caps, and installed the sprocket between the two.

After that i adjusted the tensioner as per the manual.

murr50 wrote: the engine is a replacement. Previous owner said it had around 40000km, but i cant be sure....

Those timing marks never line up exactly unless you are lucky.
Deck height, gasket thickness, chain wear and factory build tolerances etc all add up to making each engine fractionally miss timed but within designed parameters which is why you rely on the pin count and not any other measurement.
The recommended replacement mileage for the roller cam chain is 40000 miles but they usually last much longer.
You would need to measure the stretch using the factory manuals method to determine how worn yours is.
The only way to achieve design spec timing is to use slotted sprockets and degree them in.

We'd like to know how a camchain wears (stretches) to begin with when it's constantly bathed in clean, liquid lubricant that is some of the best known to man.

Good Ridin'
slmjim & Z1BEBE

slmjim+Z1BEBE wrote: We'd like to know how a camchain wears (stretches) to begin with when it's constantly bathed in clean, liquid lubricant that is some of the best known to man.

Good Ridin'
slmjim & Z1BEBE

Although this is about automotive applications, almost all of it also pertains to the KZ.
www.agcoauto.com/content/news/p2_articleid/338

zed1015 wrote: .....The recommended replacement mileage for the roller cam chain is 40000 miles but they usually last much longer.....

Is there something that documents that 40,000 mile spec, and was that for a specific model? My KZ650 has 60,000+ miles and the cam chain is still well withing the specified limits. Other KZ650 owners, such as RonKZ650, have logged way more mileage than me on the KZ650 original cam chains. Ed

Per FSM 1977~79 KZ1000 camshaft chain
where stretch suspected
Measure length @ apx 5kg pull force
standard 20-link length = 155.48~155.71mm
service limit = 157.8mm

The few manuals I have on hand just say the cam-chain lasts a long time without suggesting a specific mileage consideration.

Later hyvo style cam-chains reportedly last even longer.

Good Fortune!

650ed wrote:

zed1015 wrote: .....The recommended replacement mileage for the roller cam chain is 40000 miles but they usually last much longer.....

Is there something that documents that 40,000 mile spec, and was that for a specific model? My KZ650 has 60,000+ miles and the cam chain is still well withing the specified limits. Other KZ650 owners, such as RonKZ650, have logged way more mileage than me on the KZ650 original cam chains. Ed

The genuine z900/1000 factory dealer service manual gives both recommended mileages and stretch/wear tolerances for the service or replacement of certain parts and the listed 40000 was the rule of thumb we used for checking all the roller cam chains.
The 650 roller cam chain is pretty much the same spec but as mentioned they usually last much longer ( and of course the 650 one may have a bit of an easier life ) but at that sort of mileage it's worth checking especially on a machine that is new to the owner.
I presume Kawasaki (like any other manufacturer) play it safe and recommend replacement of parts based on the worst case wear conditions.