Any of yous guys that are gonna replace their water pump seal, here is some helpful hints.
Yamaha still sells the mechanical seal, I paid $13 for it. The oil seal is a 21mm O.D. x 10mm I.D. x 5mm thick (10 21 5). The bearing for the impeller shaft is a open 6000 series one. I used a PROMATE 1" 12pt socket to drive in the impeller seal (1/2" drive socket, std, not deep) instead of the "special tool" that yamaha recommends. I used a little Yamabond 4 around the mechanical seal and a little axle grease around the oil seal.
I just got done doin it all myself. Works great!
FYI
(http://www.click-smilie.de/sammlung/aetsch/aetsch004.gif)