TOPIC:

KZ Riders,
I've got a hell of a mystery and I'm hoping you all can help me out with your thoughts and experience. I have a 1988 KZ1000P (stock) I've been trying to get road worthy. It has had top end noise the whole time I've had it, and I've been having a hell of a time diagnosing and curing it. I'm afraid to ride the bike, lest the engine blow up.

The noise sounds like lose valves or lose timing chain, or possibly an exhaust leak. Here's the really weird thing about the noise: the bike sounds fine when you first start it up. Then, once it has gotten good and warm, the noise starts up and winds up getting pretty bad. It's definitely top-end, and it's definitely the kind of noise (ticking/clattering) you'd expect to hear with timing chain or valves.

I have inspected and adjusted the valves and they are all now between 0.05 and 0.15 mm, which is what the manual calls for [a few of the intake valves are right at about 0.15 mm].

I replaced the stock automatic tensioner with an APE manual tensioner, and adjusted the chain, per APE instructions.

I have replaced all the copper exhaust crush rings, and have even doubled them up, to ensure there's no exhaust leak.

Having done all this, the top end noise is unchanged.

The timing chain does appear to be a bit stretched, but seems to be at about the outward end of the service limit.

The timing chain guides looked good, from what I could see, when visually inspecting them, with the valve cover off.

I checked for play in the pistons (with the engine cold), and did not find any.

I removed the oil pan, looking for detritus of busted chain guides and was surprised to not find anything. There was some black sludge at the bottom, but that was about it. No chunks of chain guides. I think some of the black sludge may be from the clutch plates, as the clutch feels pretty worn/slippy.

Seems like the valve lifters and cams are getting plenty of oil circulation, so it seems the oil pump is working as it should and there is no top end lubrication issue (I have also changed the oil filter).

Does anybody have any idea what in the hell might be up with this bike? I'm about to shit can this thing, but I believe there is still potential here for a nice ride. It just does not sound at all safe to ride with this top end noise.

What do you all think? Any ideas much appreciated.

Thanks-- happy new year.

 

Happy New Year!

Please post some pictures of the bike and engine.
 
How many miles on the bike, and how long have you owned it?

Happy New Year!

You may have already done this.
Take a long screwdriver.
Put the handle end against your ear.
Put the blade end against the engine.
See if you can triangulate where the noise is coming from.

Thanks. I will try this. Part of the mystery that may speak to the source also is the fact that the noise is not present when the bike first starts up, but comes on as the bike warms up. Does this suggest anything to you?

It sounds like something related to temperature change.  Visual checks are fine but now you need some data.  Compression check, plug condition, exhaust pipe temperature check.  Oil pressure....what oil are you using?

No where did I read you cleaning and  balancing  the carbs

Possibly a loose valve bucket.
Ally head, s/steel bucket. When warm ally expands at a much lower temp than s/s hence loose when warm and bucket rattles in head. 
Did all the recess have equal  puddles of oil in them when you did the shims? 

 

Thanks Hardrockminer. The compression on all four cylinders, measured hot and cold, is very good (around 130/140 psi on each). The plugs all looked healthy. I'm using 10w-40 oil.

I cleaned and balance the carbs. Would top end engine noise like this come on only after the engine warms up if the cause is uneven carburation?

Warren3200gt, I think you're on to something here! This sounds like a likely culprit. I did not see equal puddles of oil in each pocket (and the bike was on the center stand). If this is the issue, what would the fix be? Is there any solution other than replacing the head? Could replacing the lifter buckets do the trick?

Firstly you need to check the oil volume in the recess's. If one has considerably less oil than the others you need to determine why. 
Has you had any media blasting done? I have seen bikes where the Cross drilling have not been cleaned properly and only have partial oil supply to the cam bearing/s.
If one looks less oiled, fire up the engine with the cam cover removed and with a sheet of cardboard curved over the engine. It will be obvious if one cam bearing is not getting an equal amount of oil by the oil thrown off the cams onto the cardboard. 
The lack of oil on that cam bearing will mean that bucket is relatively dry and the head ally head has worn before the stainless bucket has. 

If that is the case the only true fix is a different head but you have no guarantee it'll be any better than the one you have. 

There is a suzuki bucket which is a few thou larger diameter but getting it to fit is a lot of faffing with very fine grinding paste. You need 2 buckets, one to work with and one to use in the engine after the clean up. 

If, and it's a big if,  this is the issue it's a real ball ache position to be in. 
Once you sort the the oiling issue (if needed) you can run it without it causing further damage, it'll just be noisy. 

Obviously starting with the cam cover off applys to engines with a top idler sprocket. If you have a morse type cam chain DO NOT try this. 

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Man, I hope this isn't the case, but it does kind of make sense, given that the noise only starts up after the engine warms. I'll check things out with the valve cover off and see how things look. Quick question, though: do you think it is possible for the timing chain to be responsible for this noise, even though it is now tensioned with an APE manual tensioner? That is to say, could an old timing chain be worn in some kind of way that would still act up, even with the manual tensioner in play?