This is what I did, right or wrong, but I researched it enough from this website, and I feel confident and so far it works great for thousands of miles...
When I converted from points to electronic ignition I bought the ignition from a 550 and a combined reg/rectifier from a 750 that had electronic ignition.
What I'm saying is that different model kz 4cylinder reg/rect will work on the 650 engine, as loudhvc points out, but I would stick with a reg/rec from a points bike if thats what you have for ignition.
When you locate a reg/rec keep the same number of wires going in and coming out, I think some have different amounts, not sure tho'...
If you know what model the new reg/rec comes from then you can dig up a wire diagram from that bike and compare it to a wire diagram for your bike, the colors won't match but the function will be ok and at least you will know how to match the connections up.
You should be able to find a used one on ebay for a lot less than $50, but you take your chances with used electronics. I happened to get lucky.
I just did a search on ebay with "regulator rectifier kz" in the search box, and there are quite a few for sale, especially for the 650, check it out.
Post edited by: OKC_Kent, at: 2006/08/18 18:06