Clutch Drum/Chain Sprocket - Stihl 021 Service & Repair Manual

4. CLUTCH, CHAIN DRIVE, CHAIN BRAKE, CHAIN TENSIONER
4.1

Clutch Drum/Chain Sprocket

- Remove the chain sprocket
cover.
•
Disengage the chain brake by
pulling the hand guard toward
the front handle.
•
Remove the E-clip (1).
•
Remove the washer (2).
- Remove the rim sprocket, if fitted.
•
Pull off the clutch drum/chain
sprocket.
6
•
Take the needle cage out of the
sprocket.
- Clean and inspect the clutch
drum/chain sprocket.
!
80%
Important: If there are noticeable
wear marks on the inside diameter
of the clutch drum, check its wall
thickness. If it is less than 80% of
the original wall thickness, fit a
new clutch drum.
Note: If the clutch drum has to be
replaced, also check the brake
band - see 4.4.2.
•
If the clutch drum/chain sprocket
is still serviceable, use No. 120
emery paper or emery cloth
(grain size approx. 120µm) to
clean and roughen its friction
surface.
Reassemble in the reverse
sequence.
- Clean stub of crankshaft.
Wash needle cage in clean white
spirit and lubricate with grease -
see 11.2.
- Replace damaged needle cage.
100%
- Rotate clutch drum/chain
sprocket and apply slight
pressure at the same same until
oil pump drive spring engages
properly.
- If rim sprocket was fitted, re-
install it with the cavities facing
outward.
021, 023, 025