Tearing into my free Kz750 Engine

I hate to be a bearer of bad news but I don't see anything salvagable in the block, pistons rings junk, piston junk, cylinders junk, I would even be hesitant about the crank, hence with that much rust, wrist pins probably froze to connecting rods.

I was only talking about not having to bore out cylinder block, OF COURSE rings, pistons, probably,

after looking again maybe not as bad as u think, I dont think what rust there is , is intrusive

If you look at the picture of the the block, no. 2 piston has the outer half of the piston gaulded to the block not sure how you could get away without a total resleeve on that but anything is possible

from the picture I cant tell that, I'm guessing based on the fact that the rest of the motor look real damn good , by that I mean it doesnt seem to have been in peril from prolonged moisture. That light orangish rust is not an issue from my experience, prolly come off easy, IMO some water must have gotten in through the spark plug holes cause i dont see anything else, I mean look at the valves, pretty damn clean considering

i have not looked at many cylinders, but imo i think it needs a rebuild. mine was really bad, but not that bad and its getting overhauled. cutting corners is like wiping your ass a little bit.

stonemaster wrote:

from the picture I cant tell that, I'm guessing based on the fact that the rest of the motor look real damn good , by that I mean it doesnt seem to have been in peril from prolonged moisture. That light orangish rust is not an issue from my experience, prolly come off easy, IMO some water must have gotten in through the spark plug holes cause i dont see anything else, I mean look at the valves, pretty damn clean considering

This is what I'm seeing also, Stone. I will take better photos one I have them apart - these were with my cell phone. So far it's only oil and water as far as I can tell. Should be pretty obvious if any water got into the cases when I drain it out/get the cylinders off. The rings still seal on all four pistons, too, as they have been soaking in penetrating oil/mystery oil mixture. And again, only #1 was frozen, the others are fine.

I know there's tractors out there that get rebuilt with much worse...this thing can't be that fragile... :woohoo:

DoubleDub wrote:

stonemaster wrote:

from the picture I cant tell that, I'm guessing based on the fact that the rest of the motor look real damn good , by that I mean it doesnt seem to have been in peril from prolonged moisture. That light orangish rust is not an issue from my experience, prolly come off easy, IMO some water must have gotten in through the spark plug holes cause i dont see anything else, I mean look at the valves, pretty damn clean considering

This is what I'm seeing also, Stone. I will take better photos one I have them apart - these were with my cell phone. So far it's only oil and water as far as I can tell. Should be pretty obvious if any water got into the cases when I drain it out/get the cylinders off. The rings still seal on all four pistons, too, as they have been soaking in penetrating oil/mystery oil mixture. And again, only #1 was frozen, the others are fine.

I know there's tractors out there that get rebuilt with much worse...this thing can't be that fragile... :woohoo:

yea if ur lucky maybe u can salvage the pistons, rings are cheap. as are pins a circlips,

Finally got the cylinders off. Things got really tight at the bottom of the cylinders, not sure why as they are much cleaner than the top is. All piston pins move freely, just a bugger to get the snap rings out. The pistons may/may not be toast. Need to get better pictures, but a couple of the the rings seem to be completely compressed and stuck to the pistons. Once I get all four pistons off (taking another breather break) I'll try cleaning up the pistons to see if the rings come free.

The #3 and #4 pistons are the only two that have buildup on the upper part of the bore. I'm going to try to desolve/clean up this buildup and then move on to other areas of the motor. Not ready to build it back up yet, but I'll have the bore checked out before decided whether I go with the 810cc kit or not.

Pictures later this weekend, hopefully.

I was looking at rings for my '80 750 (stock), and I thought that they were a bit harder to find and kind of expensive compared to my 550. I know by the time you find an over bored piston it was just as cheap to go with the 810 kit.. It's been a few years since I looked at any prices though. Might have to resort to ebay...

Just think, it's only January. We got another 4 months at least until it gets warm enough out and the roads aren't sloppy.

Good to know - thanks!

Kawasaki.com shows the .020" and .040" oversize rings as canceled. Bummer...guess I need to save up for some turbo rods and the wiseco 810cc kit.

Since I've disposed of my 750 four project I have a Vesrah complete gasket set, a complete set of OEM seals (crank seals, shifter seal, etc), and a set of standard rings, left over.
If any of these will help PM me.

So I finally got the pistons free today (been busy around the homestead, but now that the wife is back in school I have a lot more free time...).

They are in pretty bad shape, the rings are all stuck flush with the piston walls, not sure if they will free easily or not. I think they need a warm bath in something slightly corrosive...suggestions are welcome!



I'm still clinging desperately to reusing these pistons, but I'm losing faith. An 810cc kit might be in my future.

I removed the oil filter once the pistons were free (no frame, so I wanted to remove some weight before trying to drain the cases) and to my horror all that came out was clear!

I removed the drain plug and this is what came out of the oil pan:



Not good. Glad I drained it.

I started to take off the stator cover so that I could remove it before tearing the cases apart, but one of the screws was rusted/frozen/stripped. I'll have to drill the head off (hopefully) to free it up. Slow progress, but then I don't have the cash to put it back together yet so I'm glad I'm not tearing through it. I'll tear it down, check everything out, figure out what it needs to be done right, and then start ordering parts.