Royal Enfield 250 CLIPPER, Workshop Maintenance Manual

Page: 15 / 96

ROYAL ENFIELD WORKSHOP MANUAL
PAGE 15
C18
All "Super 5," "Continental," "GT" and "350
Bullet" models, and later type "250 Clipper,"
"Crusader Sports," and "250 Trials" models
employ an additional filter, through which the oil
passes on its way from the crankcase to the return
pump. This filter is situated inside the primary
chain case. (See Section C, Fig. 1).
17. Breather
The efficient operation of the breather is of
paramount importance to the performance of the
engine because it acts as a non-return valve
between the crankcase and the outside atmosphere,
causing a partial vacuum inside the crankcase and
the rocker box on the cylinder head.
This partial vacuum stops the passage of oil
down the valve guides and prevents other oil leaks
which could be caused by a pressure building up in
the crankcase. Equalising holes are drilled between
the chaincase and the crankcase and between the
chaincase and the top of the oil tank.
Early Models
The breather consists of a flattened oil resisting
rubber tube located on the front of the crankcase
between the engine bearer plates.
Later Models
Later models have a metal tube extending from
a flange which is attached by three screws to the
top of the crankcase in front of the cylinder.
The underside of the flange has three
overlapping circular recesses, the middle one
communicating with the breather pipe and the two
outer ones with the crankcase. These outer
recesses contain one thin steel disc in each, which
are free to rise and fall with the pressure or
depression in the crankcase. A thin steel base plate,
with two vent holes of smaller diameter than the
discs fitted below the breather flange, prevents the
discs wearing the aluminium surface of the
crankcase.
18. Primary Drive
The primary drive from the engine to the
gearbox is by an endless chain from a sprocket
mounted on splines on the crankshaft to the clutch
sprocket, which is incorporated in the clutch itself,
and is mounted on the gearbox mainshaft.
The correct tension of the chain is maintained
by an adjustable slipper with a chilled cast iron
bearing surface accessible when the chaincase
cover is removed. An inspection cover is provided
in the chaincase so that the chain tension can be
checked without the removal of the chaincase
cover.
19. Clutch
There are four types of clutch (see Section E).
All are of the conventional plate type, having
pressure plates on the driven part and friction
plates on the driving part, including the sprocket
which is lined on both sides with friction material.
The friction material used gives smooth
operation and freedom from slipping in the
presence of oil.
20. Gearbox
The gearbox is built into the back part of the
crankcase and can be completely dismantled with
the engine in the frame.
It has foot control with an indicator on the top
of the crankcase. All gears are in constant mesh,
changes being effected by robust dog clutches. The
kick-start mechanism is incorporated in the
gearbox.
A full description of the operation of the
gearbox is given in Section E.
Gear ratios: "Crusader 250" (earlier
models):
1st Gear ........ 16.96 to 1
2nd Gear ........ 10.44 to 1
3rd Gear .......... 7.83 to I
4th Gear ... ...... 5.80 to 1
Gear ratios: "250 Clipper", "Crusader 250"
(later models) and "Crusader Sports":
1st Gear ............. 18.0 to 1
2nd Gear ............ 11.05 to 1
3rd Gear ............ 7.80 to 1
Top Gear ........... 6.14 to 1
Gear ratios : "Super 5" "Continental" and
“GT”
1st Gear ............. 17.4 to 1
2nd Gear .......... 12.82 to 1
3rd Gear ............. 9.57 to 1
4th Gear ............. 7.52 to 1
Top Gear ........... 6.02 to 1
Gear ratios : "250 Trials" (earlier models):
lst Gear .............. 27.83 to 1
2nd Gear ........... 20.37 to 1
3rd Gear ............ 13.71 to 1
Top Gear ........... 8.02 to 1
Gear ratios : "250 Trials" (later models):
1st Gear .. . 32.0 to 1
2nd Gear . .. 23.5 to 1
3rd Gear .. . 15.9 to 1
Top Gear ... 9.45 to 1
Gear ratios : "350 Bullet"
1 st Gear ... 15.1 to 1
2nd Gear .. . 9.27 to 1
3rd Gear ... 6.7 to 1
Top Gear . .. 5.15 to 1
1. Removal of the Primary Chaincase Cover
(Near Side)
First place a tray under the engine to catch the
oil which will escape when the cover is removed.
The chaincase cover is on the left hand or driving
side of the engine.
Remove the driver's footrests.
Remove ten screws and draw the cover off.
In refitting the cover see that the faces are
clean and apply jointing compound sparingly.
Special care must be taken to ensure that the
oil seal which is pressed into the cover and which
fits over the end of the crankshaft is not damaged
and it should be smeared with grease before the
cover is refitted.
See also that the Neoprene seal and tube
which connect with the bottom of the oil filter are
in their recesses in the chaincase cover. The seal
should be replaced if worn or damaged.
The rev. counter drive fitted to the
"Continental" primary chain case is best removed
by means of the two hexagon headed screws, as
although the presence of the drive does not affect
removal of the chaincase it is far safer and easier
to remesh the rev. counter drive on its own, with
the chain case already back in position.
2. Removal of the Generator Cover (Off
Side)
Take out the silencer fixing bolt and the pillion
footrest, disconnect the front exhaust pipe
bracket, and remove the exhaust system complete.
Remove the kick-start and gear-change levers,
the gear indicator pointer and the driver's footrest.
Remove five screws and the cover can then be
drawn off, giving access to the generator and the
gear-change mechanism.
3. Removal of the Rocker Box
Cover
The rocker box cover can be removed after
unscrewing a single central nut. In replacing the
cover, see that the gasket is undamaged or, if
necessary, fit a new one.
4. Removal of the Petrol Tank
The petrol tank is attached to the frame by a
rubber-mounted stud at the front, and is clipped at
the rear to a rubber sleeve surrounding the top
tube. To remove the tank, unscrew one attach-
ment nut, tap out the stud and, after disconnecting
SECTION C18
Service Operations with Engine in of Frame
the petrol feed pipe, the rear of the tank can be
pulled upwards to release the clip and then lifted
clear of the frame.
5. Removal of the Dual Seat and Rear
Mudguard
The rear mudguard, mudguard carrier and dual
seat are removable in one unit after merely
slackening off the two nuts on the rear suspension
top fixing brackets about 1
/
4
in. and pushing the
bolts in to release their heads from recesses on the
inside of the carrier attachment brackets. Stand
behind the machine, grasp the lifting handles on
each side and pull the mudguard assembly
upwards until the attachment brackets are clear of
their respective bolts. Now pull backwards until
the clip at the front of the mudguard carrier is free
from the backstay bridge tube of the frame, when,
after disconnecting the rear light cable, the
complete assembly can be removed.
When replacing, engage the front clip first and
drop the assembly into position. When tightening
the nuts make sure that the heads of the bolts are
right home in the recesses on the inside of the
carrier attachment brackets. Re-connect the rear
light cable.
6. Removal of the Tool Box and Air
Filter
Take off the dual seat and mudguard as des-
cribed in Subsection 5 and the tool box can then
be removed by unscrewing four nuts and bolts,
having first disconnected the leads to the battery,
coil, rectifier and switch.
7. Primary Chain Adjustment
Access to the primary chain adjuster is gained
by removing the primary chaincase cover as
described in Subsection 1.
Beneath the bottom run of the chain is a
curved slipper on which the chain rests and which
may be raised or lowered by turning the adjusting
screw, having first slackened the locknut. A hair-
pin spring is fitted to the slipper to hold it against
the chaincase and prevent bouncing.
Do not adjust the chain to be dead tight but
rotate the engine slowly and, while doing so, test
the tension of the top run of the chain by pressing
it up and down with the fingers. Adjust the
tension so that there is about
1
/
4
in. up and down
movement at the tightest spot. Re-tighten the
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