40 Series 4180 Powerhead
: Crankshaft (1) and flywheel (2) 
are an interference fit.
The crankshaft and flywheel are 
pressed together with such force 
that the flywheel cannot turn on the 
crankshaft.
For this reason the mating 
surfaces must be free from 
grease and oil.
The conical interference fit ensures 
the flywheel is exactly centered, and 
runs smoothly with a minimum of 
runout.
: The key (3) is used only to 
position the flywheel in relation to 
the crankshaft (correct ignition 
timing).
: The nut (4) pushes the flywheel 
(2) onto the crankshaft (1) to 
achieve the required interference 
fit.
– Remove the clutch, b 7.6.1
: Remove the hex. nut (1).
: Mount puller (1) 4119 890 4501 
to the flywheel with M6 x 25 
screws (2 and 3), and pull off the 
flywheel.
: There must be no signs of cracks 
or other damage on the flywheel 
(1) and magnet poles (2).
If this is the case, install a new 
flywheel.
Installing the flywheel 
– Clean the stub of the crankshaft 
and the flywheel hub bore with a 
standard commercial, solvent-
based degreasant containing no 
chlorinated or halogenated 
hydrocarbons, b 12
– Check Woodruff key or integrally 
cast key for damage and replace 
key or flywheel if necessary.
: Fit the flywheel in position.
Make sure it is properly seated.
Key (1) in flywheel must engage 
slot in crankshaft stub.
: Fit the hex. nut (1) and tighten it 
down firmly, b 3.4
– Install the clutch, b 7.6.2
7.7 Flywheel