Service manual
SERVICE
AND
REPAIR
Drive Chain
Adjustment
A
properly
adjusted
drive
chain
(figure
5)
should
have
a
1/8-
to
1/4-inch
slack.
Check and
adjust
chain
as
follows:
•
Remove
the
locknut
securing
the
chain
cover
top
and
remove
chain
cover
top.
•
Rotate
the
upper
sprocket
to
tension
one
side
of
the
chain
and
then
check
the
opposite
side
for
proper
slack.
If
adjustment
is
required,
loosen
the
screws
(1)
securing
the
cam
uprights
(2)
on
each
side.
•
Rotate
the
cam
(3)
counterclockwise
to
tighten
or
until
the
chain
is
properly
tensioned.
Hold
the
cam
in
this
position
while
tightening
the
cam
upright
bolts
(1)
on
each
side.
Be
certain
the
lateral
align-
ment
between
the
drive
clutch
and
the
driven
clutch
(4)
is
maintained
while
the
cam
upright
bolts
are
tightened.
•
Recheck
chain
tension
before
replacing
the
chain
case
cover.
To
Remove
Variable-Speed Drive Selt
•
Remove
the
drive
chain.
Refer
to
paragraph
To
Remove
Drive
Chain.
•
Remove
the
clutch
guard
assembly.
•
Loosen
the
locknut (9,
figure
5)
and
serrated
washer
(10).
During
reassembly,
apply 10
foot-
pounds
torque
to
the
locknut
(9).
•
Push
the
driven
clutch
toward
the
drive
clutch
sufficiently
to
allow
removal
of
the
variable-speed
drive
belt
from
the
drive
clutch.
•
Remove
the
locknuts
(7,
figure
4)
securing
the
bearing
clamps
(8)
and
remove
the
bearing
clamps.
During
reassembly,
apply 5
foot-pounds
torque
to
the
locknuts
(7).
•
Lift
the
driven
clutch
(9) and
drive
belt
clear
of
the
brake
assembly
(10) and
remove
the
variable-
speed
drive
belt.
•
Install
replacement
drive
belt.
Use AMF
Part
No. 37172
on
Model SD15P10B; AMF
Part
No.
1002110 on ModeISD18P21A; AMF
Part
No. 1002147
on Model SD18E25B; and AMF
Part
No. 349140n
all
other
models.
8
NOTE:
Variable-speed
drive
belt
installation
pro-
cedures
are
the
reverse
of
removal
except
that
the
belt
must
first
be
place
around
the
driven
clutch
and
then
around
the
drive
clutch.
After
installation,
per-
form
the
drive
chain
adjustment,
variable-speed
belt
adjustment
and
the
drive
clutch
alignm
en
t
procedures.
Variable-Speed Drive Selt
Adjustment
Proper
tension
for
a new
drive
belt
should
be
ob-
tained
when
the
clutch
centers
are
set
to
the
B
dimension
shown
in
figure
6
for
the
applicable
model
snowmobile.
A
B
C
(TORQUE)
MODEL
NO
.
FT-LB
.240
1G-3/4
45
SD15P10B
.300
10-3/4
70
S
D18P27A
.300 1G-3/4
70
SD18E27A
.
300
11-1/2
70
SD18E25B
.
300
10
-3/
4
70
SD18E20B
.300
11-1/2
90
SD18P2
1A
Figure 6
ENGINE
JLO
295
HIRTH
399
HIRTH
399
KOHLER
399
HIRTH
493
HIRTH
634
CLUTCH
780
910
910
910
910
1190
HOLDDOWN
NUTS
VIEW
0
Proper
tension
for
a
used
dri
ve
belt
is
obtained
when
opposite
sides
of
the
belt
can
be
squeezed,
between
the
drive
clutches,
to
the
following
dimensions
as
measured
between
the
top
and
bottom
outside
surface
of
the
belt.
SD15P10B
SD18P21A
SD18P27A
SD18E27A
SD18E25B
SD18E20B
2-3/4-
to
3-1/4
inches
4-1/4-
to
4-3/4
inches
4-
to
4-1/2
inches
4-
to
4
-1
/2
inches
4-
to
4-1/2
inches
4-
to
4-1/2
inches
1002472
()