Pistons in LTD- cylinder

[Habbeli]

Kawasaki,,,, how did you think this??? 

The small marks are the piston ring pins

LTD-piston in a LTD-cylinder


Invader-piston in a LTD-cylinder


But then it also breaks the rings 

[Habbeli]

Opps, forgot to change the resolution of the camera 

[80 Kawi]

1980 4/6 ltd piston...and  Invader piston..interchangeable...debatable?

[Interceptor398]

The only difference between the Invader and 4/6 pistons is the ring pin location and some 4/6 pistons came with a coating to help with the brake in.  I hear of people using the Invader pistons in the 4/6 but it looks a bit risky.

[Habbeli]

does not get it then better with LTD's pistons 

[gixxer6]

The 4/6 pistons are breaking rings? 

[Shawn]

Please elaborate on how the rings are getting broken ? The pin inside the ring groove of the piston fits into the end gap of the ring in order to keep it clocked (Keep it from rotating) so that the ends of the ring don't catch on any of the port edges inside the cylinder wall causing breakage. This is a critical issue as allowing the ring to catch will surely cause serious damage within that cylinder and possibly the rotating parts or crack the cases or cylinder. The Invader engine has fewer transfer ports than the 4/6 so the end gap alignment needs to be examined closely. The pistons skirt cutouts (open areas below the wrist pin hole) can also affect breathing on a two stroke. Piston port engines (which the Kawasaki is) tend to be sensitive to this as evidenced by their appetite for different carb slide and needle shapes than reeds or rv's. The skirt openings look to be clocked slightly different in your pics ? Make sure they don't cover any of the transfer ports. If so you must either use pistons with skirts which don't or you need to grind away the skirt to uncover the port ? Grinding to remove material (weight) affects balancing. The pins within the ring grooves can easily be relocated by a competent machine shop to properly align the ring end gaps. Ring end gap should always be checked to be sure it's enough. More is way better than not enough. Too little and the ends butt together from heat expansion forcing the ring outwards against the chrome bore leading to seizure.  If you mock up one cylinder leaving the rings out, mark all the ports and ring end gap location, then slowly rotate the crank by hand you could check all these issues.