Further...… The zxr7 and likewise are 34mm slave pistons and the one I have is 33mm. Also, I've seen a Honda slave cylinder (see pic) with exactly the same embossed brand mark on it - so I'm guessing it is a Japanese component manufacturer that supplied parts to more than one brand(?). If so, that'll make it even harder to track down. The image attached is from an add for a Honda VT1100 Shadow clutch slave. The manufacturer's mark is identical to that on mine! Mine probably had a part number and I assumed that it has been polished down to nothing.... Of course the mark could mean that the Honda slave shown is an OEM part and not what would have been on the original Honda!! Arghhhh - this is hard.