4.9 Nikasil coating of cylinder
Nikasil is the brand name for a cylinder coating process, developed by the piston
manufacturer Mahle. The name is derived from the two materials used in this pro-
cess - a nickel layer into which the particularly hard silicon carbide is inbedded.
The main advantages of the Nikasil coating are:
●
excellent heat dissipation and thus better power output
●
low wear
●
low weight of the cylinder.
N
OTE
: T
HE WORN COATING CAN BE REGENERATED AT LOW COST PROVIDED THAT THE CYLIN
-
DERS RUNNING SURFACE IS FLAWLESS
.
4.10 Exhaust control, clutch cover
– Remove screws
1
and take off the bearing support.
– Take cup tappet
2
, adjusting spring
3
and auxiliary spring
4
out of clutch
cover.
– Take off water pump cover, remove allen head screw
7
and take off water pump
wheel
8
.
– The centrifugal timer
9
can be pulled out of the bearing.
– Clean all parts and check for signs of wear.
Check clearance of the
BEARING OF THE ADJUSTING LEVER
bk
.
Check
PIN
A
of adjusting lever for wear.
Check
LINKAGE BALL HEADS
bl
for clearance.
Remove
CIRCLIP
bm
and check
AXIAL BEARINGS
bp
and
WASHERS
for signs of wear.
If the
WATER PUMP SHAFT SEAL RING
bn
is replaced, it should be coated with Loctite
242 on the outside.
Check
GROOVED BALL BEARING
bo
for clearance
4.11 Preassembly of clutch cover
– Grease water pump shaft seal ring
bn
and mount centrifugal timer
9
.
– Fit adjusting spring
3
, auxiliary spring
4
and cup tappet
2
in the clutch cover.
– Fit bearing support with control lever and linkage
bl
. Secure both screws
1
with Loctite 242.
– Mount water pump wheel
8
, coat screw
7
with Loctite 242 and mount with
washer.
– Mount dowels of the water pump cover.
– Position gasket and fix water pump cover with 5 collar screws. The two screws
mounted at the dowels must each be provided with one copper gasket.
4.12 Reed valve housing, intake flange
N
OTE
: R
EED PADDLES
A
GRADUALLY LOSE TENSION THROUGH OPERATION
,
RESULTING IN
POWER LOSS
. D
AMAGED OR WORN REED PADDLES MUST BE REPLACED
. I
F THE REED
B
SEA
-
LING SURFACES OF THE REED VALVE HOUSING ARE ALSO DAMAGED
,
REPLACE THE COMPLETE
REED VALVE HOUSING
.
!
CAUTION
!
S
ECURE ALL SCREWS OF THE REED VALVE HOUSING WITH
L
OCTITE
242.
4
1
2
3
4
7
8
13
14
9
10
11
12
A
15
1
2
7
8
9
Summary of Contents for 250 1998
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