Wheel widening

A word about Kosman; I have a friend with a KZ1300 in the States & he had his wheel widened by Kosman about the same time I did. He got his back & he wasn't pleased with the quality at all, they left the welds visible & he didn't bother fitting it.

An interesting bit, thank you. I don't have any first hand personal experience with them, I know he was talked about within Vmax community and there are bikes around with wheels done by him and sometimes also the wheels show up for sale. But I do remember one guy saying the wheel came apart when riding. There was some discussion about it and and I don't remember the details now. I think they changes some way of doing this aver time, I suppose addressing issues. Anyway, these were the cheapest affordable aftermarket alternative if someone wanted to have a radial rear tire.

That's not good about the wheel falling apart? This company said that grinding the weld seam was extra? Maybe I can do it myself to save a few dollars?

But I do remember one guy saying the wheel came apart when riding.

This is exactly what my first point of concern was specifically about. Re-Welding can induce stresses. The correct heating/re-heating should be done to eliminate these stresses and return the entire rim to the correct metallurgical state. I'd also be concerned about the welding process. Anything done "by hand" would be a NO GO for myself. If the "shop" didn't have some form of automated MIG process ( wire feed and rim rotation set up for one continuous weld) - also a NO GO, for me.
Personally: I would not consider removing the weld myself. This should be a "process" also to eliminate any chance of under-cutting. A seemingly minor flaw could be a source of failure.

I'm somewhat surprised that I haven't seen anyone adapt a wheel from a different make/model to the drive system on the KZ1300. The drive plate that engages the cushion drive is a 7 lug plate, but I'm sure that with a bit of work, that could be altered to a 5 or 6 lug plate. I'd rather take a chance on the drive plate crapping out before I had a wheel rim fail.
Looking at a 2000 Yamaha R6 wheel hub looks a lot like the KZ wheel hub. 17 X 5.5 would allow a 190 tire. That would look nice and fat on the back end of the 13