Here are the basics of the belt:
Made by Gates but only available through the BMW dealer.
Costs from 190-290$ per belt not including sprockets
Sprockets should be replaced or filed down depending upon their condition
It is normal for the belt to move to the outside of the sprocket in reverse; it will go back to its original position when going forward!
How long will the belt last?
It could last forever but Dailyrider replaced his at 90K and some others at 25K
All depends on your riding style, outside weather factors, destruction by penetration and sprocket conditions
My belt has a whole; ok to drive?
There are several owners that rode several thousand miles with a belt that had a whole in it.
Be prepared for it to fail at some point and time eventually, the belts are pretty though.
Belt part numbers:
27 72 7 659 995 changed to 23 00 76 69 995
has 174 teeth
old: 27727659995 tooth belt
new: 23007669995 main shaft
In order for your belt to last a long time you will need to check its tension regularly!
If the Belt needs to be replaced you can read up here on how it is done!