Blown rod bearing!

OK here is the initial reason for my complete teardown and rebuild. Last October she started banging hard out of nowhere. I drove a mile and called for a pickup. Today I removed the damaged piston. When I finally get around to cracking the case, I'll have pics for yall. So I'm doing a new piston and rod bearing. Bore has no scratches, head shows no damage, neither does the crank, although I have not seen inside the bearing housing and the shaft itself. Anyone think of any other potential damage to look for?

oops!

If you plan on keeping the engine stock I have a bunch of pistons from my KZ1300 which are identical to the 650 pistons and are in excilent shape. Here is the link for the Vyton valve seals for your bike.
cgi.ebay.com/ebaymotors/Kawasaki-Z1-KZ90...5QQitemZ250080563966

Post edited by: otakar, at: 2008/03/01 18:20

Sorry this happened to you. What do you think caused the problem? Insufficient, old, or poor quality oil, low oil pressure, or something else related to lubrication? How many miles on the engine? Had the engine, ignition, carbs/airbox or exhaust been modified? How well was it running before this happened? I think it would be of interest to other owners to see if this could have somehow been prevented or predicted as this could save somwone else from suffering the same problem. Thanks, Ed

I have a specific question. Was that on number 4 cylinder? If so This is from someone who leans the bike on start up and leaves it to warm up on idle. The number four bearing doesnt get as much lube as the other bearings due to where it is....uphill to the oil flow. Same thing happens to the cams on that side, oil leaves as fast it it arrives.

This happened to the #3 cylinder and yes I do lean for rest but usually set on her level to warm up. She has not has a center stand in quite a while, although I did buy one on ebay only to find I still need a spring and rod. Oil flow may be an issue. I'll check all ports when I crack the case. I have been a 500mi oil change freak. All four carbs torn down, cleaned and rebuilt. I have more inspecting to do. ***THX OTTO*** I will continue to update post with pics as the disection precedes. More input and questions are appreciated.

Hi Marty
I have some bad news for you and some good news for you. I did find out that the stock pistons for that bike are not available any more NEW. They are also NOT exactly the same as the 1300 pistons, but the 1300 pistons WILL work. The 1300 pistons have a lower dome on them because of the longer stroke of the 1300. This will mean that the 1300 pistons will have lower compression in your bike by about 3/4 of a point. The other good news is that I should have enough pistons in exilent shape to provide you with all four. All I would have to do is clean up the other three. O your other choice is that you might be able to pick up this set for a song.
cgi.ebay.com/ebaymotors/Kawasaki-KZ650-K...dZ1QQsspagenameZWDVW

Hay Marty, I just thought of something else. Since you have the cases apart, just hogg out the cylinder sleve pockets in the upper case and drop in a set of 750 jugs and pistons. A stock set of cylinders and pistons can be had for a song. Even I have a set of those and I don't even own either the 650 or 750. If you cant find a set for cheeper you can have mine for $75 + $15post, stock block and pistons. This is another option you have.

otakar wrote:

Since you have the cases apart, just hogg out the cylinder sleve pockets in the upper case and drop in a set of 750 jugs and pistons.

Just a heads up: this will only work with a set of jugs off a 1980 750, later 750 jugs do not have the provisions for the idler sprocket shafts and won´t work with the single roller cam chain setup on pre-81 650s.

I will have to look and see which set I have.

Below is a pic Mark Wing posted in this thread. The block on top is a post-1980 750, the bottom one is a 650 block with two arrows pointing to the provisions for the cam chain idler sprocket shafts - if your 750 block has these provisions it´ll work.



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Post edited by: OnkelB, at: 2008/03/02 12:25

And here's the original original thread

We have covered the 650 to 750/810 conversion several times