Remove front chain and take off clutch assembly (use clutch with-
drawal tool 040449).
Remove rotor, engine Sprocket, watch for distance piece behind it.
Remove three countersunk screws fixing rear portion of chaincase to
engine.
Remove crankcase breather pipe.
Remove front engine plate bolts and take away engine plate.
Remove both footrest arms,
Remove three bolts passing, through rear engine plate and crankcase.
Release the top and bottom gearbox fixing nuts a few turns,
Move the crankcase assembly forward, Lift and take it out of the frame,
NOTE—If a magneto is fitted, follow details given for removing
Scrambler type engine.
Warning: When the engine has to be re-installed, connect the two oil
pipes at the crankcase end first.
Screw home as far as possible the two nipple nuts by finger application,
to avoid the risk of cross threading. Finally tighten without undue force
with suitable spanner.
Removing tappet guides. Both guides are a force fit in the crankcase, the
guide with its tappet are removed together from inside the timing chest.
It is preferable to effeot this operation with the engine in a dismantled
state, with both halves of the crankcase bolted together to avoid distor-
tion and give additional support.
Heat the crankcase in the vicinity of the guides, sufficiently to enable
them to be drifted out. Use the same method to refit the tappet and guide.
The two dowel pins for the cover can fall out, when the crankcase is
heated. When the guide is correctly located, the outside diameter is just
flush with the crankcase face.
Dismantling the rocker box. The design of the rocker box is basically the
same on all single cylinder models. Some Lightweight 250 c.c. models
do not use a valve lifter, but a later type rocker box 044034 can be used
on this type of engine. Use the following parts for the valve lifter
assembly:—
Valve lifter lever 013969.
Valve lifter spring 044035.
Valve lifter screw 000451.
Valve lifter washer 000039.
Valve lifter lever ring 014523.
Valve lifter cable 026254.
Valve lifter lever assembly 026239.
The rocker box is supplied with bushes. The existing rockers, etc., can
be transferred.
It is best to refer to Fig. 3 to understand the assembly sequence of the
parts used in the rocker box. To dismantle, place a box spanner (that will
fit the nut 000003) firmly in a vice. Invert the rocker box, place one of
the two rocker spindle nuts into the box spanner.
Using an open end spanner, release and remove the rocker axle nut
inside the rocker box.
Using a soft drift, tap out the axle, when the inside rocker will drop
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