TOPIC:

No eBay APP ID and/or Cert ID defined in Kunena configurationI bought a set of these 1mm overbore KZ750 twin pistons. The manufacturer states piston clearance is  .025mm measured on the coating. This seems really tight, especially for an air cooled bike, although they are cast pistons and this is measured on the coating. Factory clearance spec is .043-.070mm.

I did read this on the the translated page
"In connection with an installation clearance reduced by approx. 0.025 mm (possible due to the MOS2 coating), this results in the best possible and desirable smoothness in connection with the highest operational reliability and the lowest oil consumption!"

Am I worried about something that I shouldn't be? I don't really know much about this coating


 

If you trust the translation, go with it.  It's either MOS2 coating or abradable powder coating on them. 

The extra coating is meant to wear off and allow the piston to fit the cylinder as tightly as possible, after break-in.