its not strictly necessary to replace. I have turned the roller marks off a couple of these on a lathe and they always worked well. The boss is not hardened and cuts easily. You can polish any burrs on the backer plate that holds the rollers as well. I think the issue is primarily the rollers get caught in existing grooves and do not engage properly, removing the surface defects is all it takes.
Yes, that should work for sure (if worn grooves not too deep and hub of starter gear not reduced in diameter too much). Maybe one even could find slightly bigger rollers for this case too. But...
Starter clutch of this design lasts around 100 000 km on motorcycles like KZ650, KZ750, Zephyr 750. At least I have this data confirmed on my own Zephyr 750, yet one local Zephyr 750 and owner of another Zephyr 750 from Australia reported the same mileage without the starter clutch failing.
I have no particular reason to replace this starter clutch except one: with all new parts it will be around 100 000 km without worries about the starter clutch.
With the starter clutch repacked there was nothing to stop me from finishing the Kawasaki KZ650 engine assembling. Workbench was ready for another (mostly final) stage of the process.
To drive the secondary shaft in place I used an improvised driver: a piece of aluminum pipe of suitable diameter plugged with aluminum blank. Since not only the cylinder head, but also camshafts were installed beforehand, I had to work on the secondary shaft and other engine bottom components with the engine positioned a bit weirdly.
Oil pump was followed by the oil pan (along with a new genuine gasket, O-Rings and bolts).
Please pay attention to the oil pan’ bolts. It’s the first time I with my attention to details went so far as choosing even engine bolts in various finishes: chrome plated for polished covers, matt zinc plated for painted parts, and gloss zinc plated for semi-polished oil pan.
After this I turned my attention to clutch components.
I was glad that Oksana was in the workshop at that time: with 130 Nm of torque for the clutch nut it’s better to have a pair of spare hands to keep the clutch holding tool in place when torquing the nut.
Recent wonderful ride through the rain of falling autumn leaves on the cafe-racer gave me an idea for Halloween pumpkin carving. So this year it’s Jack O’Lantern motorcycle rider. And even as I myself prefer full face helmets, who knows what Jack O’Lantern helmet preferences is? It’s likely to be an open helmet, or how else everyone would see his charming grin?