New pistons question...KZ1100B2 (82 GPz1100

The 1100 has a bad cylinder liner.
I can buy these funky looking unused pistons, use my old wrist pins, and get
the block bored for what it will cost me to buy one sleeve and have it put in.
Local machine shop wants more to install a sleeve than bore the whole block, plus
I have to buy the sleeve.

I'm curious about if and how well they will behave. They are like 13.5 to 1
compression in a kz but if I put them in the 'J' they won't come up as far
in the cylinder and should drop down to around 11:1.

Center is pretty tall but the skirts look real short.

FUNKY looking piston.



Post edited by: Duck, at: 2006/04/09 18:12

changing the sleeve isnt that hard to do .toss the new sleeve in the freezer toss the block in the oven to heat it up real good and pop the sleeve out,warm it up some more and drop the new sleeve in and let it cool off.what size are those pistons,do you get rings with them?:whistle:

Is the edge around that valve pocket really sharp enough to cut you, or just an optical illusion??
13.5:1 and gas ported, I guess you already know those pistons were not designed for street use

I don't like the top of those pistons, looks like an invitation to detonation to me.

They are 76mm and come with rings.
Not real expensive and the stock 1100
sleeves have enough material to take out
to 76mm.

I don't like the top of those pistons, looks like an invitation to detonation to me.

I believe they are as sharp as they look.
Carboned up, they'd definitely have some hot spots.
For street use, I'd expect them to have to come out
for a cleaning from time to time.

changing the sleeve isnt that hard to do .toss the new sleeve in the freezer toss the block in the oven to heat it up real good and pop the sleeve out,warm it up some more and drop the new sleeve in and let it cool off

I mentioned this to the guy at the shop and he said the 1100 sleeves are cemented
in and have to be bored out. I mentioned heating and a press and he said
that the liner expands with the block and it's a PITA to press out, hot or cold.
I got the impression that they didn't want to do it

I'm gonna bring it home and toss it in the oven tomorrw and see for myself!

Post edited by: Duck, at: 2006/04/09 19:04

I'd be rather suspicious of someone telling me a steel (or cast iron) liner will expand as fast and as far as an aluminum block.

Sounds to me like the guy was scrambling for an excuse to avoid doing it.

If that edge is anywhere near as sharp as it looks, you won't need carbon to have a hotspot. I wonder how long that edge would last before it melted? I'd do some serious work on the top of those pistons before installing them, you can afford to cut them down quite a bit and still have more than enough compression for the street.

You are not planning on keeping that motor for a long time and putting a lot of miles on it, are you?

Production motorcycle pistons have skirts on them for a reason

Post edited by: steell, at: 2006/04/09 21:47

Production motorcycle pistons have skirts on them for a reason

I would not use it as a commuter and don't think I'd keep it too long. I'm
much more fond of the kz engines. Without a kick start, it's just not a
motorcycle.

If I get the things, the mini-skirt will make for another question...
How much clearance, piston wall to cylinder wall?

Post edited by: Duck, at: 2006/04/09 22:13

For piston to cylinder wall clearance, you really need to contact the manufacturer, because they are the only ones that know what alloy they used, and the rate of expansion for their piston design. Otherwise it's just going to be a WAG

Those pistons showed up at the door yesterday. The skirts are 'normal' length. They looked short in the photos but next to the stock 72.5's they're the same. They are also incredibly light. They came with new rings.

Before I haul them and my block over to the shop on Monday for bore and hone, I'd like to ask if anyone has an unused set of pistons and rings for a 'J' motor in 76mm and would rather have these KZ 13:1 gas ported Venolia beauties.

If I don't hear by the time I head out to the shop on Monday...Machinist says he'll know the alloy and clearances when he sees the pistons.

-Duck

did you find out if he had anymore of those pistons?

Unless he's sitting on them, I think these were it. I sent email asking but no reply. He hasn't listed any more on ebay. They are really light. Like 260 grams.
Found some FT500 parts on the porch this AM so will probably be working on that instead of trekking to machine shop. Will keep looking for some less radical pistons for the 1100.

Post edited by: Duck, at: 2006/04/15 16:08