Converting an 18" rear wheel to a 16"

Thanks for the measurement z1kzonly !! I measured the hub on my KZ650b wheel and it's about 9 3/4", so as you said, it's a bit smaller than the 900 / 1000 bikes.

What's your thoughts on this, my KZ650 hub looks to be 1/4" to 3/8" narrower than yours. That's 1/8" to 3/16" on each side. So if I used the spoke kits used to convert the 900 / 1000 bikes like yours, but with my 650 hub, all it would do is straighten the spokes out a bit, or have them running closer to a 90 deg angle from the hub. Assuming there wasn't an issue with the length of the spokes, wouldn't this work ?? I'm thinking there's enough extra spoke threaded into the nipples to allow for this.

Or I Buy the rim I want and then have Buchanon's make the spokes to fit. Which might be the smarter way to go. I guess I'm trying to limit my purchase from Buchanon's as I find some of their pricing to be a bit high compared to what can be found elsewhere. But I'm not aware of another place that makes spokes to fit, so they got me there. I have a lot more money to put into this project, so I have to limit myself as much as I can.

Thanks for the info DoctoRot !! I forgot to post I decided to go for the expanding type, or hub brake on the rear wheel. Yes I will have some fab work ahead of me on this. I purchased the hardtail conversion from Lowbrow Customs for this project which lowers the rear 2.5" and stretches it 3.2". It uses the front portion of the factory frame, so it eliminates getting the DOT involved and having to get a new title for the bike.

Here's a pic of it....

I understood you want a drum brake/ "expanding type" hub. What axle diameter are the plates of that hardtail?

This is from the manufacturers website........

Stretch: 3.2 inches
Drop: 2.5 inches
Axle Slots: 20mm (3/4 inch) x 65mm
Int. Axle Length: 9.25 inches

The kz650 uses a 17mm axle. Its probably easiest to find a z1/kz900 drum hub which already uses 20mm. Otherwise you will need to do a bearing conversion, bore the brake plate, and make a custom bearing spacer for inside the hub.

They make spacers \ sleeves, I think there referred to as top hats, as with a little imagination they look like the top hats men used to wear in the 1920's I believe. These top hats are machined to fill the void between the axle and the axle plates on the frame, thus eliminating the need to go through all the work you've referred to. Depending on where you get them, they range from $8 to $15. That will save me time and money going that route.

more than one way to skin a cat