Join Date: Jun 2002
Location: The Deep South of Vermont
Drive line lash
With the bike on the centerstand and the transmission in gear rotation of the rear wheel will occur to the point where the lash in the drive line is taken up, and engine compression stops the turning.
This will probably vary a little bit depending on what gear is selected.
Gear wear, improper shimming of the pinion gear in the final drive, and bearing wear in the tranny could all contribute to excess drive line lash; however the amount you describe sounds normal.
A certain about of "slop" in the gears is engineered into the transmission. Lots of factors influence transmission performance but a really "tight" gearbox would be a hard shifter so a limited amount of play is engineered in to improve shifting behavior. This transmission "slop" and normal gear spacing in the final drive and engine driveline add together to create the "free play" you are noticing at the rear wheel.