I seem to remember 720mm circumference for the ringear. That would make 2mm per degree.
Mike, you're close, but Greg Bender measured twice and got 759mm. I'll just quote him to save trouble:
The circumference of the ring gear is 759 mm (I measured twice). The number of teeth on the ring gear is 96 (I counted thrice). So, one tooth on the ring gear is equal to 7.90625 mm in circumference. One degree is circumference is equal to 2.1083 mm. Therefore, one tooth on the ring gear is equal to ~3.75° of circumference. If full advance is 33°, then that would equal 8.8 teeth.
I counted 96 teeth multiple times too. Greg made a round-about calculation with rounding error to conclude there are ~3.75° per tooth, but actually that value is exact (360/96 = 3.75).
2mm per degree is not far off from 2.1.
Moto