Stihl MS 661 Manual page 38

2
1
: Slide the assembly drift (1)
1108 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 6.8
1
: Pull out the needle cage (1),
inspect and clean it, replace if
necessary.
MS 661, MS 661 C-M
Installing
2 1
– Lubricate the needle cage with oil
and push it into the connecting
rod.
: Line up the piston so that the
arrow (arrow) on the piston crown
points towards the exhaust port.
The assembly drift (1) can be
pushed through the installed snap
ring.
– Place the piston on the
connecting rod.
: Slide the assembly drift (1)
1108 893 4700, small diameter
first, through the piston and small
end (needle cage) and line up the
piston.
: Lubricate the piston pin (2)
with oil.
: Fit the piston pin (2) on the
assembly drift (1) and slide it into
the piston.
– Prepare snap ring for installation
with installing tool
5910 890 2212.
Fit the snap ring so that its gap
(arrow) points up.
: Fit installing tool 5910 890 2212
with the sleeve's taper (flat facing
up) against the piston boss, hold
the piston steady, center the tool
shank exactly and press home
until the snap ring slips into the
groove.
Make sure the tool is held square on
the piston pin axis.
– Check that piston rings are
properly seated and correct if
necessary, b 6.8
– Install the cylinder, b 6.5
– Reassemble all other parts in the
reverse sequence.
37