‘76 KZ900 LTD. Need some advice.

Wookie58 wrote:

zed1015 wrote:

Mikaw wrote:

Your bike was stock 66mm bore. If it’s 70mm, then either the block has been swapped out for a 1000 (1015), or the 900 block was bored and the 1000 sleeves installed. That might explain why they don’t fit. This is assuming the the 1000 sleeves vs the 900 are a larger OD. I have never thought to check. 

This is slightly incorrect.
The stock 900 liners can be bored to 71mm ( 1045cc) so it's likely they are on the stock max 70mm oversize on stock liners.
1000 liners are a larger OD so a 900 block needs boring for them to fit.
Loose sleeves are not uncommon either because of factory tolerances or they've been cold pressed out and back in which drags material from the alloy block and lessens the fit..


 

If the liners are as loose as they appear to be, will they not "rock" forwards and backwards during normal running causing the block to oval and the liners to chew the head gasket ?

Never seen any that are more than just a loose slip fit with a slight drag.
If they were somehow that loose to enable them to rock i wouldn't used them.
Sleeve retainer can be used to secure loose liners.


 

If it's of any help...I have a set of 903 cylinders bored to 1015.  I don't need them and would gladly donate them if needed.

Thanks guys. I pulled this motor apart because of the broken cam chain guide. It ran perfectly fine and always has since I bought it in ‘77. With the liners seated, there is zero play. The pistons look just fine and believe it or not, I can actually still see a bit of cross hatch pattern inside if the light is just right. No grooves or signs of abnormal wear at all.

I find it odd that a guy would take a brand new bike and do a big bore kit on it, but that simply must be the case. That also might explain why the liners slide out, keeping in mind this was done almost 50 yrs ago.

Before you put it back together be sure to wash the pistons well being sure there is no carbon under the rings. That can ruin good bores. Don't ask me how I know.  If you can see the original cross hatch the rings may still be good. Pics of the pistons can help identify what you have. I suspect you have the early Wiseco pistons that are NLA. 
Steve

I will post some pics. The motor doesn't smoke or burn any oil. I figure since I have it apart I might as well replace the rings anyway. Maybe not since I'm not really sure which rings to even buy?

As Steve mentions 
If a Wiseco kit they have changed  the designs of pistons and rings over the years.  and the rings are no longer available
I called Wiseco right after a early design change in mid 80's  for new rings 
And since they just changed the design they sent me a new complete piston kit for the cost of the rings they had just redesigned, 

Looking at the photo of your pistons that you posted. From what I can see the small valve reliefs plus the directional arrows on the piston dome tells me they most likely are cast O.E.M. pistons. What puzzles me if they are stock Kz1000 pistons why would someone take the time to install oversize sleeves when they could have just bored the 903 cylinder out to 70mm..............

 

Its common practice to replace the camchain when you teardown one of these motors especially when it has been run loose enough to break that camchain guide.

I’ll bet these pics will help.

Looks like you an drop a Wiseco 1015 kit in there and have a little more power. 
Steve

Looks like your pistons have a one piece oil ring. I never remember any Kz1000 coming from the factory with one piece oil rings. I know the 900 motors used a one piece oil ring, but I thought all the Kz1000's came with the now standard three piece oil ring. Even the factory Kawasaki replacement ring sets for the 900 motors were superseded to ring sets with a three piece oil ring.  I kinda remember people were using Honda CB450 pistons in the 900 motors in the very early days of the Z1 before anybody made big bore kits for them. Don't know what CC those std. or oversize CB450 would make in a 900 motor. And the factory CB450 pistons used a one piece oil ring!!!



 

I just looked it up the CB450 Honda has a 70mm bore!!!! Interesting............ Maybe those are CB450 pistons and rings!!!

CB450 and 500T pistons were used in early 900's as bigbore kits to 1015cc but they are higher comp.
I've had a couple of motors with them in.
See attached pic of the last one.
The OP's pistons appear to be stock 1000 compression regardless of oil ring type which may be aftermarket replacements if they used stock used 1000 pistons or similar and fitted new rings.