I think they are Cruzinimage (ebay) seller's pistons that someone had coated. I think this is the thick type soft powder coating which will wear off and then piston slap. Some say count the coating before bore job, others say not so much and it will "break in fit". I have played with powder coatings before to try and close up gap... but don't last. The latter idea makes sense to me these days, but I don't use that thick stuff anymore
There are other harder coatings that will get you 0.0015" on forged pistons and about 0.0001" on cast.
Cruzinimage pistons are OK but usually some subtle error when they we reversed engineer. May or may not matter.
If I do a T500 again that I want to rev up, I would go with forged like Wossner $$$. They have thinner coating that seams to last too. Also if you want less slap, keep clearance to ideal not on the far end of tolerance range. And if slap more reason to go forged for stronger skirt like forged.
If you got the coin don't cheep out if piece of mind matters to you. Dang ,piston and bore condition sure makes a difference in performance, engine noise and long term reliability.
must admit, i prefer the endless [plain wire] circlips, even though they are very difficult for me to fit
this sort are easier to fit, but easier to flirt out, ruining barrels, pistons, heads. don't fit those crappy circlips
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.