Piston - Stihl MS 231 Manual

Installing
Before installing, clean the
crankshaft, b 14
Heated ball bearings must be
installed quickly because the
crankshaft stubs absorb heat and
expand.
: Position the ball bearing (1) with
its open side facing the
crankshaft.
– Heat the inner bearing race to
approx. 150°C (300°F).
: Push the ball bearing (1) onto the
straight crankshaft stub (clutch
side) as far as stop.
: Position the ball bearing (1) with
its open side facing the
crankshaft.
– Heat the inner bearing race to
approx. 150°C (300°F).
: Push the ball bearing (1) onto the
tapered crankshaft stub (ignition
side) as far as stop.
42
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: Lubricate the needle cage (1)
with oil and push it into the
connecting rod.
1
– Install the piston, b 6.8
– Install the crankshaft and new oil
seals, b 6.5
– Install the engine, b 6.5
6.8

Piston

– Remove the engine, b 6.5
– Remove the crankshaft, b 6.6
The assembly drift passes through
the installed snap ring. Therefore,
only one snap ring needs to be
removed.
– Remove the snap at the side with
the recess.
1
: Use a suitable tool to grip the
hookless snap ring at the
recess (arrow) and ease it out.
1
2
: Slide the assembly drift (1)
1110 893 4700 through the
installed snap ring and push the
piston pin (2) out of the piston.
If the piston pin is stuck, release it
by tapping the end of the drift lightly
with a hammer.
Hold the piston steady during this
process to ensure that no jolts are
transmitted to the connecting rod.
– Remove the piston.
– Inspect the piston rings and
replace if necessary, b 6.9
Installing
– Pull out the needle cage , check it
and replace if necessary.
: Lubricate the needle cage (1)
with oil and push it into the
connecting rod.
MS 231, MS 231 C, MS 251, MS 251 C
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