the 81t is very small. I am not sure how you are rubbing the belt - I use RW pinions 15/16t with the 87 AE spur (which is thicker than the 96t kit spur) and the only time I had a problem with meshing was with my LRP motor which was faulty (the motor shaft actually moved inside the can)
I currently use a 5.5 Nosram X11 brushless motor and have no problem, the motor shaft is long enough to get a good fit with the pinion. I've never had a need to use a long boss pinion but I can see that some people might need to as not all motors are the same - but the long boss might be the solution.
|