Select first gear.
Straighten the tabs of the locking washer on the central nut.
Remove the plug on the right side of the crankcase.
Hold crankshaft with Allen key (arrow).
Warning! Central nut (5) is secured with Loctite 243 and considerable torque is required to release it.
Unscrew central nut (5).
Remove the locking washer (4).
Use puller, BMW No. 008400, to pull the chainwheel off the mainshaft.
Installation is the reverse of the removal procedure: pay particular attention to the following.
Lightly coat the mainshaft with Optimoly MP 3 before installing the chainwheel.
The sprocket must be installed with the "EXT" marking on the outside.
Install a new locking washer (4).
Clean threads of central nut and mainshaft, coat threads with Loctite 243 and install nut.
Bend up tab (arrow) of locking washer.
Tightening torques:
- Central nut on mainshaft (clean thread + Loctite 243): 140 Nm