I think AMinkman is right. You might have to get the suspension revalved/resprung to compensate for the larger wheels & longer swingarm.
Go to the suspension forum and ask for Jeremy's opinion on this.
Here are some part numbers I got from
buykawasaki.com .
2000 KX100
swingarm- 33001-1543-TX (80 is 33001-1542-TX)
front rim- 41025-1356
rear rim- 41025-1347
front wheel assy- 41090-1111
rear wheel assy- 41090-1112
The site does not list any part #'s for hubs on the 80 or 100. Check with a dealer to make sure the 80/100 use the same hubs!
I suggest pricing aftermarket spokes/nipples & rims and comparing the prices with stock parts. If the aftermarket parts are close in price go with them.
One other thing, I think the 80/100 use different size sprockets.
Hope this helps!
RJ