1990 ZZR600 Crank Seal Leak

[Diddums]

Afternoon all. I'm in the process of restoring a 1990 ZZR600 (D model), which I definitely didn't buy whilst under the influece on ebay.

Anyway, I'm using this to learn how to do stuff myself, and today I got it started for the first time, but it's got a leaking crank seal on the right hand side of the engine.

Here's a vid:

https://www.youtube.com/shorts/AZc_ATZKelY

Is it possible to DIY this? Can it be done without splitting the engine? I'd like to give it a go myself if possible, but not really sure on where to start!

Cheers.

[stinkwheel]

Wow, that's pretty bad. There's a trick I've seen used to sneak crank seals out but I'm not sure if it'll work on your bike specifically, depends how the seal fits and if it has a ridge on it to hold it in position.

Basically, you carefully drill two small pilot holes in the seal and screw self tappers into them. You then wrap a long-ish loop of wire between the two screw heads and use a hammer to tap against the loop and hopefully pull the seal out. Then much ado with bits of pipe to drive the new one in.

My main question is why is it like that? I've never seen a crank seal leaking so badly on a japanese 4-stroke. So is a main bearing on the way out and that's killed the seal? Is the crankcae breather blocked?

Why is oil leaking out when it's running but not when it's parked? It's suggesting to me it's pressurised in there and if the breather's working properly, there should be a slight vacuum in the crankcases.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Diddums]

[stinkwheel]

Again, I'm not familiar with these engines but looking at pictures, there's a thickish black hose coming vertically off the top, back right of the engine. The other end is are generally connected into the airbox somewhere. That should be the crankcase breather. Usually a case of making sure it isn't pinched or blocked. Some have a one-way valve either in the hose or internally so they can blow but not suck.

I suppose one test would be to run it with the oil filler cap off (meaning you can't really get positive crankcase pressure) and see if the leak goes away.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[jeffyjeff]

Appears to me that the leak could be between the seal and the counterbore; seal to crank nose might be leak tight. I agree that the leak appears to be pressurized in origin, but probably does not leak at rest because the oil level is below the level of the crank. Could it be that someone has worked on this prior to sale, and that the seal was mis-installed, or even the wrong seal fitted? More targeted, focused observation might reveal more clues.

PS I have used sheet metal screws to remove crank seals before, but instead of wire, a small prybar was used to work the seal loose. Mostly on automotive, but it did work on my BMW R1150. That seal looks a little small for this trick to work. Works best when the seal is encased in a metal ring.
____________________
History shows again and again how nature points out the folly of men - BOC

[Diddums]

[Diddums]

[Diddums]

Just in case anyone's interested, here's a build log of the bike and my learning adventures along the way:

https://forums.overclockers.co.uk/threads/kawasaki-zzr600-progress-thread.19001282/

[jeffyjeff]

[Diddums]

[stinkwheel]

If it can't be done from the outside, splitting one of those engines isn't a horrible job. I mean, it's not fun and will push your comfort level a long way but it's a horizontally split engine so you can take it out, flip it upside down and take the bottom off without having to strip the entire engine like you do with vertically split engines.

A plastic bag over the breather can't have been helping. I have a breather on one of my bikes (a very different one to yours mind) which periodically got the end of the hose pinched over before I rearranged everything. It used to literally piss oil out of every gasket and seal when it happened.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[jeffyjeff]

[Diddums]

[Diddums]

[stinkwheel]

[A100man]

[Diddums]

A bit more theorising and faffing this afternoon. After pulling the pulse generator wheel off, I had a close look and it does look like these holes are oil scavenging ports:

https://i.imgur.com/LG9CkD1.jpeg

https://i.imgur.com/U63KB3M.jpeg

This coupled with what looks like rathre old oil stains in the casing means I bolted the cover back on, topped it up with oil and fired it up. Either it seizes and I have to yank it apart anyway, or it works. So far, so good:

https://youtube.com/shorts/S6rT1YYNcyE

This weekend I'll flush and seal the tank, clean the airbox and bolt it all together properly. Then balance the carbs, do an engine flush and replace the oil and filter with the final stuff. The current oil is sacrificial Castrol stuff.

Assuming there's any oil left in it of course

[A100man]