51 Tooth rear sprocket

[grayracer513]

I've been using a 51 rear and 13 front on a 2000 426f.

While you guys are comparing notes, remember that the primary gear ratios of the bikes from '04 and before are different from those from '05 and later. The difference between the two is about identical to the change you get from changing one tooth on a front sprocket, so that a 14/49 on a 426 or early 450 is the same approximate overall ratio as an '05 or later with a 13/49.