Z1OwnersClub GB

As the title says have oil pouring out of cylinder 1 on start up.
This happens as soon as the bike starts and continues as long as it is running
Not by bike just trying to help someone resolve the problem.

z900 crankases opened up to accept z1000 barrels.


thought it was a problem with ring clearance so replaced the barrels and pistons with a freshly rebored set.
Still pouring oil out of exhaust port 1


replaced the head with a known good one .Ths head was on my 1000st and all the exhaust ports showed no oil residue on that bike.
the only thing that was from the old head were the cams and the cam shells.
Problem still there.

Engine starts OK
Oil is getting up to the head
engine turns over smoothly
crank does not SEEM to have any unusual play
visually no sign of a bent rod.
no witness marks or unusual scoring on the new pistons or bores
liners on the rebored barrels do not appear to be cracked.

Any thoughts on how/why oil is getting to No1 exhaust port?
Compression is around 130psi on all cylinder when cold.
Cannot really run it to get a hot reading.

To me it sounds like a crack in the head somewhere between the exhaust port and the material around the guide.

Assuming everything is fitted corectly ....you have changed everything apart from the exhaust ..have you tried running the bike without the exhausts fitted ,, I have known valve guides moving within the head and only noticeable when the engine has warmed up ...

Leak down test may highlight the problem!!

He says the head has been replaced and the barrels too.
The whole top end has been replaced and the problem still exists.
Doesn't make sense unless the replacement parts have the exact same fault which would be an unlikely coincidence.

Sure it's oil and not fuel?

I also think it could be fuel not oil.

its very unlikely to be oil if you have changed the cylinders & head ? its probably fuel levels do you leave it on the side stand ? make sure the overflow pipes are not blocked. is the engine breather clear? is the engine oil overfilled

floydsz1 wrote:I also think it could be fuel not oil.

I was thinking the exact same too as i was reading through the thread !
If that was Oil thats leaking into the exhaust port you'd have other magor sign's & symptoms (&most likely route would be a crack from ex valve bucket bore ...but never heard of that...most unlikely ) & if it was cracked on the Inlet side it'd be smokin like Volcano on Woodbines !
More likely a sticking or bad seating float needle valve, dumping to the inlet track but I do think you'd probably smell & see something too. I'd swap the needle & seat from and to another cylinder thats running OK & see if the problem is then transered to the donor cylinder.
That guy should have kept all Cam Shells with their original head too...obviously he does'nt grasp the consept of Line Boring or the use of Plastigauge along with a Micrometer, O well, he might be lucky....hope so . Johny B

camshaft bearing shells are not available in anything other than standard sizes they are not like main & con rod bearings where you have to match the bearing to the crankshaft & the crankshaft to the crank cases

z1bman wrote:camshaft bearing shells are not available in anything other than standard sizes they are not like main & con rod bearings where you have to match the bearing to the crankshaft & the crankshaft to the crank cases

Yeh ......I'm aware of that. I lost the plot there.... I was mistakenly thinking of swapping Cam Caps about for some reason ...Doh !

If it is actually oil then there must be a breathing issue.

It is an odd one

.we have been starting this without exhausts fitted.
The oil that is thrown out coats the front mudguard and fork leg within a minute or so.
I understand the fuel idea but its deffo oil


the other 3 cylinders are not showing oil in the exhaust ports so crankcase pressure seems less likely.

The reason I changed the cams and shells was to keep them mached together.
The 1000st engine uses larger cam sprockets than the earlier engine.

We had changed the stem seal on the earlier head but with it still pouring oil we thought a crack between the oilway and exhaust port was the cause.

The z1000st head was still complete from when I removed it a few months ago to fix a couple of damaged spark plug threads.

will let you all know if we ever resolve it but its getting so expensive I suspect we will be replacing the engine for something else.

remove the head & support the cam chain with a screwdriver with a little tension then spin the engine over with the starter. look to see if oil is coming past the rings in no cylinder ?

blockage in the oil gallerys/lines?