Diagnosing a lovely knocking noise

[motorang]

Same as for the 600 cc models
here is a quick how-to:
viewtopic.php?f=54&t=3577&p=35678&hilit ... ain#p35678

Found this one about XTZ660 noise as well:
viewtopic.php?f=54&t=2659

Good luck!

Andy

[dan3]

I'll have a look at the cam chain tomorrow, thanks for your help

[dan3]

Hmm. Cam chain adjuster is working fine.

Oh no piston rings!

[motorang]

How many clicks did you have left?
AFAIK there are 18 clicks available in total, where the first 3 or 4 are already taken with a newly mounted chain.
For a 30.000 km engine I would expect 10 clicks left for the piston to use.

Andy

[dan3]

It had 9 clicks left, so I guess the mileage is accurate.

[motorang]

Thanks for the replies chaps. It's proved a bit difficult to really zero in on the cause, even using a screwdriver stethoscope, one thing I am sure of is that it's top end related.
I've checked that oil is getting to the top of the engine, and the inlet valve clearances. I've also checked the nut on the balancer shaft, just to be sure.
So I guess it's got to be the exhaust valve clearances, the valves themselves, pre-detonation, or the piston.
Is there an easy way to check the exhaust valve clearances? I took one of the covers off before I ran out of time yesterday and they don't seem easy to get to.
It's a 1991 3yf btw

It does not sound like a valve clearance thats off. Its not pre-detonation. Does not sound like crankshaft or small end either, most likely a piston problem. Anyway, nothing that can be fixed from the outside really.

The bike is new to you? How is the oil consumption, would you know?
Coolant level?

Andy

[dan3]

That's what's strange, it runs really well. No blue or white smoke, doesn't overheat and doesn't seem to burn any oil or coolant.

[dan3]

Hi
OK so the engine is out and I've stripped down the top end.
Does anyone know the play tolerances for the piston please? There seems to be a lot of lateral play on the pin.

[donnybach]

Mate, these specs for top end are in the clymer I have, BUT, it’s for up to 1989. I’d guess they’d probably be the same but it’s a start if they’re not. Hope it helps a little.

[donnybach]