TOPIC:

Hi All
Looking for some pistons for a KZ400 B, part number 130011001.
Is there any difference between piston part number 13001-069
They certainly look the same, just having problems find some.

Heres a picture of the 13001-069

There are two different KZ400 engines. The early model was from 1974 to 1977 and the late was 1978/79.
The early has a round dome and a flat dome and the late had just a round dome. Do not interchange them.
Why are you changing pistons?


.

I'm curious too, having much the same problem -

"The early model was from 1974 to 1977 and the late was 1978/79.
The early has a round dome and a flat dome and the late had just a round dome. Do not interchange them."

Okay - but my '79 KZ400 H takes the same part number - 13001-1001 - and these 13001-069 pistons sure look like they'd fit.

Regarding the "round dome and flat dome" vs. the "late round-only dome" comment - are the early ones high compression, or are there TWO different pistons for the early models and the ONE round-dome for the late models?  These 069's sure look like they'd fit - and they are all over the place, while the 13001-1001's are scarcer than an honest politician...what is the difference between the 069's and the 1001's?  The ones I need are 64mm (Standard) size. 

"Do not interchange them." Why is that? I'm assuming because maybe the KZ400 is an interference engine?  I can see why you wouldn't want to put high compression pistons in an engine that didn't take them, but I would think the difference between the round-top ones would be minimal as long as they were the same size, i.e. the 069's and the 1001's.  

In general terms the shape of this piston crown is determined by the combustion chamber, "flat tops" in a "dome top" engine would give low compression - "dome tops" in a flat top" engine is likely to result in some mechanical "love making" of the expensive kind  

There are 3 different pistons used in the KZ400s. 
The early models used 2 different pistons. One with a dome with a round top and the other with a flat top dome.
The late KZ400 has around top dome, which evolved into the 67.5mm bore KZ440. And not much interchanges between early and late.
The early pistons will interchange but I would run the same style dome on both pistons.
The late pistons are around .020 taller [being a metric engine probably 1/2mm. Also the the rings are thinner.
Here aresome pics for reference.
top left - late KZ400
top right - KZ440
bottom left - early round dome
bottom right - early flat dome


.