1980 KZ650 top end noise - valve train?

[TheDog]

A buddy of mine is have an issue with his top end on his 1980 KZ650 E1.

It started with an audible tap between 3000 - 4000 rpm. Took the head off and saw that the cam chain guide rubber roller bearing (?) was all chewed up.

(not our part, just a pic of it to get an idea)



Drained the oil twice, replaced the part with an upgraded tensioner from Z1 Enterprises:
(The rubber part of the tensioner that got chewed up is replaced with a gear.)



Measured all the valve shims and they were all within spec. One lifter was harder to install than the others (1st cylinder intake side? - Rear cam). Put the top end back on and the noise persists, and is getting worse. Took the bike on a short ride to see what was up and it stalled and wouldn't kick over after that.

Got it back to the shop, and the next day it would kick over but would quit after a few seconds at idle. I'll attach a video of the sound it's making.

Could this be a stuck lifter? A friend said it could be a worn/stretched cam chain? We're trying to figure out what would cause the initial problem (the chewed up tensioner). Oil starvation?

Here's a little history/background leading up to the problem
1980 KZ650 E1
~20K
The only engine work that's been done was a re-shim on a few valves a few years ago (new gaskets afterwords)
Pod filters (rejetted)
Standard oil

The bike was being run pretty hard previous to this happening (WOT - probably top speed on and off a few times on ~70 mile ride). Noticed the noise a couple days later.

Any help or ideas would be appreciated! We're taking the top end off again to see what's up and take some more measurements of different components. Thanks guys.

[Guest]

Sounds like a loose rocker.

[turnandburrrn]

Sounds like a loose rocker.

Could you be more specific? I'm familiar with Harley rockers, but I don't think this KZ has them...

Or are you saying, 'if this was happening in an engine with rockers, this is what it would sound like'

(turnandburrrn = TheDog's new account)

[Guest]

I'm saying it sounds like a loose rocker, bear in mind there are 1000's of Japanese models unfortunately, I don't have time to research every model for people when helping diagnose, so the equivalent of a rocker if it doesn't have any would be a push rod. Of course it could be chain slap but it doesn't sound like chain slap.

[Phantom309]

The Kawasaki 650 doesn't have rocker arms, nor does it have push rods. The cam lobes act on the valves directly, through inverted shim buckets. The cam lobes push the buckets downward. Between the buckets and the end of the valve stem, are shims to adjust the valve lash. The very distinct pecking sound you hear can be slack between the cam lobe and the end of the valve. I would make an educated guess it is a broken valve spring. As far as the engine stopping and not kicking over.....that is most likely a result of secondary damage, possibly the oil pump plugging with shrapnel from the cam chain tensioner? Take a compression test. That pecking could also be a piston tagging a valve that is hanging open, as a result of the afore mentioned broken valve spring, or the valve being seized in the guide in an open position. I'm guessing, after the remark about the engine being run very hard, that there was an oil starvation issue, and there could be severe damage to the lower end as well.

[turnandburrrn]

The Kawasaki 650 doesn't have rocker arms, nor does it have push rods. The cam lobes act on the valves directly, through inverted shim buckets. The cam lobes push the buckets downward. Between the buckets and the end of the valve stem, are shims to adjust the valve lash. The very distinct pecking sound you hear can be slack between the cam lobe and the end of the valve. I would make an educated guess it is a broken valve spring. As far as the engine stopping and not kicking over.....that is most likely a result of secondary damage, possibly the oil pump plugging with shrapnel from the cam chain tensioner? Take a compression test. That pecking could also be a piston tagging a valve that is hanging open, as a result of the afore mentioned broken valve spring, or the valve being seized in the guide in an open position. I'm guessing, after the remark about the engine being run very hard, that there was an oil starvation issue, and there could be severe damage to the lower end as well.

Thanks Phamton309. When we had the head off last time, we didn't see any piston with any marks like a valve was hitting it. We didn't pull the valves out to see if any springs were broken or stuck, so we'll do that for sure.

We took a (cold) compression test after we put the head back on the 1st time with the new cam chain guide. It read something like this:
1: 70
2: 80
3: 80
4: 80

I know it should be done with the engine warm, but we were just checking for any serious irregularities between cylinders. The book says a tolerance of ~50 between cylinders is "acceptable". I thought was a little much, but we only saw +/- 10.

We're going to drop the oil pan as well and get it all cleaned out. Thanks for the reply.

[Phantom309]

All those compression numbers are WAY low. The book says 150-185 is the healthy range. You got some kind of issue there. I wonder if you got one of the cams a tooth off on timing??? I'm kind of reaching in the dark, here. I wish I were there to tear into the thing......

[turnandburrrn]

All those compression numbers are WAY low. The book says 150-185 is the healthy range. You got some kind of issue there. I wonder if you got one of the cams a tooth off on timing??? I'm kind of reaching in the dark, here. I wish I were there to tear into the thing......

I don't think the timing's off. We went by the book (checked and double checked the marks before putting the cover back on). Those numbers are from a cold engine though, so we'll have to take a reading next time after it's up to normal range. It ran really well prior to the knock, and we've taken the cams out a couple times before that so we've had experience with setting the cams properly back in.

[turnandburrrn]

This top end noise ended up being the result of a shot connecting rod bearing. The bearing was shot due to a worn crankshaft. My buddy originally replaced the shot bearing, only to damage another one because the crankshaft was worn. He now has the new (used - in spec) crankshaft in (and bearing). Should be back together this coming week.