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So I recently just finished putting my motor back together on my 80 Z1R and am waiting for gas tank sealant that is on backorder. While that is in transit I figured it would be a good idea to remove the oil pan and clean the oil pump screen. Upon fighting to get the oil pan off (horray for paper gaskets that stick like glue when you try to remove them) and taking a look at the bottom I saw what looked to be small chucks of metal on the bottom of the pan. I thought to myself, great my motor is eating itself alive and has severe bearing damage and these are all metal shards and chunks. Upon feeling the chunks however, I realized they were not metal, but rather what felt like plastic. I know that the bike has no plastic in the engine and given that the bike is as old as it is, I assume that "plastic" was once rubber. Now, I've read many of the threads about how the rubber in the cam chain gears and dampers plasticize and how that can eventually disintegrate and cause the gear to become lose and for the chain to skip teeth and the valves to meet the pistons. I unfortunately did not come upon this knowledge until after I had already put the motor back together using the original cam chain gears and idle damper gear. I did replace the rubber dampers that go on top of the rods that hold those in place, but I did not know the cam chain gears were made out of rubber. I ran the bike for about 150 miles before doing this rebuild and the bike sat for 30 years before that, so my thought is that all those little chunks came from that 150 miles of riding. So i guess my assumption is that I am about to start riding a ticking time bomb. I just spent 8 months doing this motor over and am really reluctant to pull it back apart again as I am dying to ride. My question is whether or not I should ride it as it is or tear the whole motor down again to replace them, maybe if I could salvage a season out of the old gears it could become next winters project to replace those. Advice and or thoughts? (Also any hints as to how to remove that old oil pan gasket would be greatly appreciated.) Thanks

I don't think you're totally fckud... unless you decide to ride it and it self destructs.  I'm not familiar with the Z1R but wouldn't this just entail pulling the cams, removing and replacing these stupid rubber gear bushings (or whatever they are), retiming and putting the valve cover back on?  No big deal really when the flip side of that coin is not really enjoying riding anyway while imagining at any time the cams could jump some gears and destroy all your pretty valves and pistons? 

While you were in there did you inspect the rubber center roller, tensioner roller and the front guide? Do you hear cam chain noise? It might have been left by the PO which isn't uncommon.
Steve

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I don't think you're totally fckud... unless you decide to ride it and it self destructs.  I'm not familiar with the Z1R but wouldn't this just entail pulling the cams, removing and replacing these stupid rubber gear bushings (or whatever they are), retiming and putting the valve cover back on?  No big deal really when the flip side of that coin is not really enjoying riding anyway while imagining at any time the cams could jump some gears and destroy all your pretty valves and pistons? 

To replace all of the rubber internals would include removing everything down to the crankcase as the cam chain gears are sandwiched between the block and head and the idle damper is between the block and the crankcase. I would need to replace the actual cam chain gears and the tensioner guide and the rubber block guard along with the idle damper, so its fairly involved. And I suppose that certianly is one way too look at it, although I havent even had the chance to run it since the motors been put back together so not sure if I could even get it started much less enjoy the riding with all the on my mind like you mentioned.

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While you were in there did you inspect the rubber center roller, tensioner roller and the front guide? Do you hear cam chain noise? It might have been left by the PO which isn't uncommon.
Steve

Hey Steve, I did inspect the rubber center roller and the tension roller and the front guide. They each had slight creases in them from the chain and were, if i'm honest, very hard. It has been about 8 months since the bike last ran so its hard for me to remember but I dont think it had any alarming cam chain noise, and the carbs were never synced and I know that doesnt help. The pervious owner of the bike was my dad and he did very little mechanical work to it, the first owner was a father of a friend of his, who did lots of work on the bike using plenty of RVT and other janky tactics, as well as breaking a few bolts,  I know for a fact that all those gears are at least 35 years old because of this.
 

UGH!!!  Yeah that's a lot uglier than I imagined.  I feel for you brother. 

In a way you have answered your own question which boils down to do you feel lucky?  If I were in your shoes I would have no choice but to take the motor apart and check the components in question.  Is five minutes worth of riding fun worth trashing your motor?  Yes it would no doubt be a bunch of extra work and you may find all is good and these were just old pieces left in the engine, but on the other hand you may find something critical to your engines survival.  Your choice in the end...make your decision wisely.

Rick H.

Actually, there IS plastic in the engine and it often winds up in the oil pan.  There is a cam chain deflector that bolts to the front of the cylinders, on the inside.  It usually breaks and falls into the pan.  Do you have a photo of what you found?  It might also be your cam chain rollers as you suspect.  There are three of them to worry about.  One is between the cases and your cylinder block.  Two sit on the block, under the head.  

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Actually, there IS plastic in the engine and it often winds up in the oil pan.  There is a cam chain deflector that bolts to the front of the cylinders, on the inside.  It usually breaks and falls into the pan.  Do you have a photo of what you found?  It might also be your cam chain rollers as you suspect.  There are three of them to worry about.  One is between the cases and your cylinder block.  Two sit on the block, under the head.  

I actually do happen to have some photos, here they are. Sorry for the lack of focus on the finger there, maybe it'll give you an idea of size.



 

It doesn't look like the cam chain guide.  Here are some photos from an engine rebuild I did a couple of years ago.

This photo shows where the piece goes, inside the barrels.  The photo is looking down the cam chain tunnel, with the front of the barrels with the front of the barrels towards the bottom of the photo.  The round hole is the location for the bolt that holds the guide in place.

 

These photos show the piece that was laying in the oil sump.

 

 

Here is another picture of the plastic chain guide.

www.z1enterprises.com/cam-chain-guide-z1-kz900-1000-2.html

I just figured out that I've fallen prey to this exact issue. I'm getting real familiar with this engine, real fast. DOHC, thanks for the insights.