Technical data

20
Overhaul
Replacing the valve seat, exhaust port *
Grind down the valve disc of a discarded valve to just
below 27 mm (1.063 in) diameter. Push the valve stem
through the guide.
Do not push in too far - the valve disc should be just
below the edge of the seat. Spot weld the disc in
place at three points using a MAG electric welder.
Knock out the seat by hitting the valve guide with a
plastic-headed hammer.
IMPORTANT! Cover the cylinder head surface so
that it is protected from any weldning spray.
Cool the new seat to approx. -20° C (-4° F); the cylinder
head should be at room temperature (+20° C / 68° F).
Place the cooled seat on tool 884961 and knock it
down until it bottoms.
NOTE! Turn the seat with the valve face towards the
tool.
* Replaceable exhaust valve seats was introduced
from engine numbers:
Model Product No Engine No
2001 868212 46683
2002 868213 46980
868214 46912
868215 46740
868216 46760
868217 47495
2003 868219 47947
868220 46922
868221 46897
868222 47500
2003T 868223 47214
868224 46775
868226 46807
Valve springs
5. Check the free length of the valve springs and the
length when loaded.
L = Length, unloaded 42.5 mm (1.67323 in.)
L
1
= Length, loaded with 170±10 N (17±1 kp) 32 mm
(1.25984 in.)
L
2
= Length, loaded with 300±20 N (30±3 kp) 24 mm
(0.94488 in.)
Rocker arm mechanism
6. Disassemble the rocker arm mechanism and clean
the parts. Check the wear of the shaft and rocker arm
bushings. Should the bushings need to be replaced,
use the mandrel p/n 9991867 for the removal and in-
stallation, (make sure that the oil hole in the bushing
coincides with the one in the rocker arm). After the in-
stallation the bushings are reamed to a close running
fit. When installing the rocker arm shaft, it must be
turned so that the lubrication holes are facing the
valve-side. Check to make sure that the rocker arm
contact surface against the valve is concave. Minor
adjustment are made in a valve grinding machine. Oil
the shaft and install the parts.