Engine Just Blew??

79MKII wrote:

PLUMMEN wrote:

My next question was going to be "what caused this"? I was thinking that my pressure must be high. I have heard that it will get better as the engine breaks in - have you guys heard that?

The motion of the pistons does pressurize the crankcase as they move up and down. There is a crankcase vent, but there is still some pressure. BTW, I had a valve cover leak too and start dumping oil once upon a time. That's why I usually use a thin line of black Hi-temp RTV to bond them.


79MKII wrote:

PLUMMEN wrote:

Also, aren't the factory Kawasaki gaskets rubber? I'd pay extra to get a good quality rubber gasket but I can't remember for sure.

Thyey are rubberized fiber with a rubber coating on the outside. They are better than aftermarket. An OEM cover gasket can usually be taken on and off a couple of times if done carefully.

OK, cover is all scuffed up, cleaned, and a new gasket is coated with hi-tac and is setting up on the cover. Should be ready to go on the engine tomorrow.

Hopefully that will solve my oil leak and then I only have to find out why it was running so badly. The plugs all look pretty decent, so no fouled plugs. I also tested the gas cap vent and it works great. I hope to try again with another ride tomorrow.

All you folks talking about the piston movement causing pressure to build up in the crankcase do understand that there are two sets of two pistons moving 180 degrees out of phase with each other?

While one pair of pistons is moving down, the other pair is moving up, so they just push the air back and forth between them, the displacement of the crankcase never changes.

The crankcase vent is to allow piston ring blowby to escape

The KZ twins do pressurize the crankcase, then create a vacuum, because both pistons move up and down together.

bountyhunter wrote:

79MKII wrote:

PLUMMEN wrote:

My next question was going to be "what caused this"? I was thinking that my pressure must be high. I have heard that it will get better as the engine breaks in - have you guys heard that?

The motion of the pistons does pressurize the crankcase as they move up and down. There is a crankcase vent, but there is still some pressure. BTW, I had a valve cover leak too and start dumping oil once upon a time. That's why I usually use a thin line of black Hi-temp RTV to bond them.


79MKII wrote:

PLUMMEN wrote:

Also, aren't the factory Kawasaki gaskets rubber? I'd pay extra to get a good quality rubber gasket but I can't remember for sure.

Thyey are rubberized fiber with a rubber coating on the outside. They are better than aftermarket. An OEM cover gasket can usually be taken on and off a couple of times if done carefully.

werent me,i didnt say it !:laugh:

steell wrote:

RonKZ650 wrote:

As much as I like stock, I'll have to say you've done a fabulous job there on the MKII. Hope it works out as an easy fix.

High praise indeed, coming from the man that hates anything that's not stock

Almost went into shock when I read that post!!

Took the words right out of my mouth!
(hey...isn't that a song?:huh: )

Ron...we're cathin on to ya,bud.

That IS a beautiful machine though...wholly doodles!

I've never seen a valve-cover gasket do that before.I don't think you could even blame that on over torquing.
Is it possible,that it got torn during installation?(first thing that came to mind).

(edit)...just looked at the picture again,and I can see that the gasket was not torn...hmmm.

Sandy wrote:

[...I've never seen a valve-cover gasket do that before.I don't think you could even blame that on over torquing.
Is it possible,that it got torn during installation?(first thing that came to mind).

(edit)...just looked at the picture again,and I can see that the gasket was not torn...hmmm.

Right, it never did tear. It just distorted real bad and slipped out. I think it had to have been from crankcase pressure. Hopefully it will get better as it breaks in. The new gasket is installed with Hi-Tac and a roughed up cover, so it should have a much better chance of staying put. The bolts were still tight when I removed the cover. Here'a a better pic with the cover removed:

i just had to pull the valve cover off my 80 z1r and my valve cover gasket had moved much like yours has.but i was also leaking oil out the center o-ring in my three piece head gasket.i replaced my head gasket with a copper one piece(against advice i recieved from others)and some 1211.i'm hoping that works out for me:blink: .
i hope this is the cure for yours though.to nice a bike to leak oil:P .

79MKII wrote:

Oh, almost forgot...

The swingarm is from Klasmo in Germany. I had them make a 6" over version and move the shock mounts back one inch. They now list it on their site. I bought it several years ago though when the dollar was still real money. It would cost about $900 right now, compared to about $650 when I bought it. Shipping has gone way up too. I'll post a link if I can find it.

Found it - here it is:

Swingarm Link

High end American made chrome moly arms are about 1/2 that much

A couple of thoughts for you.

Are you still running stock cam cap bolts? If not, make sure the heads are low profile heads. If you've used allen bolts for the cam caps, these will likely sit too high - holding the cam cover off the gasket slightly.

As the rings are new, they may not have bedded in yet - this will allow more ring blow-by than normal.

I had a similar issue a few years ago - I pickup up my first turbo'd KZ. The previous owner put some additional ports in the valve cover - but they look crappy, so I put a stock valve cover on the bike - big mistake, the bike puked oil out just about all the gasket surfaces...

That motor shouldn't have that much blow by. Is it a big block? Who built it?

Jay

APE Jay wrote:

79MKII wrote:

Oh, almost forgot...

The swingarm is from Klasmo in Germany. I had them make a 6" over version and move the shock mounts back one inch. They now list it on their site. I bought it several years ago though when the dollar was still real money. It would cost about $900 right now, compared to about $650 when I bought it. Shipping has gone way up too. I'll post a link if I can find it.

Found it - here it is:

Swingarm Link

High end American made chrome moly arms are about 1/2 that much

Jay,
Where can you get these? Do they have pivot bearings?
Thanks

Jeff and Jay -

The cam bolts are stock - shouldn't be a clearance issue. My old gasket was twice the thickness, but this should be OK too, I would guess.

The machining was done by S&K racing in Ohio and I did the assembly myself. It is a stock block with LA sleeves that I had put in 18 years ago by a local builder. I never had any oil leaks with the 1229 kit in all of those years, but I also had an extra vent in place of the starter. This time around I had the 1229 bore increased to 1260, the max for these sleeves and a stock block. S&K also did all of the headwork.


Do you guys agree that the crankcase pressure will decrease as the engine breaks in? I only have about 50 miles on the rebuild so far.