Disintegrating Cam and Valves

Hi folks..

I have a KZ1000 J head on a 1975 Z1 bottom, running 1327 cc's.

It was running well, until it spat a valve shim out through the front of my head. I'm using an APE shim-under-bucket setup, so this was unexpected.

The exhaust valve buckets and cams on the front left (#1 and #2) were worn so badly, that the cams dug all the way through the buckets, and scooped a shim.

The head is out being welded, and I'm ordering new pieces, but I'm still not sure why this happened.

I know I was low on oil for a while, maybe a liter and a half down. I use a large oil cooler, and I don't know how much oil it (and its lines) hold.

Could my oil pump have been sucking dry? When these engines run too low on oil, is it typical for valve gear on the front left to suffer first?

Even then, it would be weird, as the rest of the buckets and cam lobes are undamaged.

Any thoughts or ideas would be most welcome..

-SkidZmark-

:woohoo:

1327 cc's , and let it run low on oil!?!?!

I think your lucky that shim didnt come right up thru you.

Oil starvation is my first guess - obviously.
Second - Tensioner installed incorrectly, clenching cam chain VERY TIGHTLY?!?! ...

Tisk, tisk.

Wouldn't ride like that again...

I would think rod and main bearings would eat it first with no oil, not the cams and lifters.

bountyhunter wrote:

I would think rod and main bearings would eat it first with no oil, not the cams and lifters.

Harder to get the oil up to the head, plus the rods and bearings may have survived on what oil is in the bottom. I'm just guessing here.

Who's buckets?

What cams?

How much time / miles were on the motor?

Over Size Valves with stock base circle cams?

What's your oil cooler capacity?

I have seen this happen sometimes. Generally it's on fresh motors. Sometimes it's from coil bind of the valve springs. Sometimes it's improper break in of the cams.

It's possible oil starvation caused this. #1&2 exhaust valves would be on the far end of the top end oil path.

If you wore thru the buckets then there is going to be a lot of metal through out the engine, I would think you need to look at the rest of the motor and CLEAN everything

What I would worry about is the fact that the ground up components are made from some of the hardest steel in the engine. This could cause some catastrophic damage to other engine parts. This stuff will inbed itself into all the soft plain bearings which it comes into contact with. I don't know about you guys, but I would check every clearance tolerance in the engine and change every bearing I could. I would also pay special attention to the wrist pin ware points.

otakar wrote:

I would check every clearance tolerance in the engine and change every bearing I could. I would also pay special attention to the wrist pin ware points.

+1

WHAT DID THE CAM BEARINGS LOOK LIKE?

Thanks KZ'ers, for the replies.

I'm using parts from APE- big block, pistons, cams, springs,shim-under buckets. The head is a lightly ported 1982 KZ1000J, with all new pieces: stock Kawasaki valves, APE springs, timing chain and guides.

Interesting that the cam bearings still look like new.

I'll admit I'm not looking forward to tearing this engine back down to the crank. It took me a couple of years to get this bike on the road.

Oh well. I shouldn't have let the motor get low on oil. It took me a long while to fix all the leaks, and I thought it had stopped leaking.

The new buckets are on the way. I'm wondering if I may be able to have the cam re-welded, or if it would be cheaper to simply buy another..

-skidZmark-

The cam bearings are the furtherest distance from the oil pump. Most of the time they are the first to go, when the oil pump is defective. Myself, I would think that a bad cam lobe or lobes, killed your buckets.

Re-welding? Ask whoever made them. A lot of companies can't regrind because the "holding fixture" or "end of the cam", is cut off when the cams are finished. Just no way to put it back, in the cam grinding machine.

I know that web-cam welds and regrinds. I sent them a set of stock 1300 cams which they welded up and reground to my new specs. I think that to do just one or two lobes should not be too expensive.