Royal Enfield 500 TWIN 1949 Workshop Maintenance Manual Download Page 23

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ROYAL ENFIELD WORKSHOP MANUAL

SECTION D1

Service Operations with Engine Removed

" Meteor 700" and "500 Twin"

Removal of Engine from Frame

Disconnect the battery leads and remove the

battery.

Remove the dual seat and petrol tank.
Remove the engine steady brackets.
Remove the air cleaner and battery carrier.
Remove the exhaust pipes.
Disconnect the electric horn leads.
Disconnect the magneto and dynamo leads.
Remove the slides from the carburettor.
Remove the rear chain and chain guard.
Remove the bolts from mudguard bracket at

rear of gearbox.

Remove the footrest bar.
Remove the bottom rear engine bolt.

Support the engine on a suitable box or wood

block.

Raise the centre stand and remove the spring.

Loosen the bottom gearbox nut and swing

the lower engine plate down.

Remove the front engine plates and horn.

Remove the nuts from the top bolt of the rear

gearbox plates and then remove the timing side
gearbox plate. The engine can then be swung
out on the right hand side.

Alternatively,

if the engine is to be stripped,

remove the primary chain case cover, the engine
sprocket and clutch and the back of the primary
chaincase. The top rear engine bolt can then be
withdrawn without disturbing the rear gearbox
plates.

2. Removal of the Gear Box

Remove the engine sprocket (Section C.1,

Subsection 26) and clutch (Section C.1,
Subsection 29).

Remove the rear half of the primary chain

case by removing three socket screws and the
chain tensioner pivot.

The gearbox can now be withdrawn from the

back of the crankcase after unscrewing the four
nuts which secure it.

3. Dismantling the Crankcase

Drain the oil tank by removing the drain

plug.

Having removed the engine from the frame

as described in Subsection 1, dismantle the
heads, barrels, pistons, timing gear, magneto,
etc., as described in Section C.1.

Remove the gearbox as described in

Subsection 2.

Remove the two hexagon-headed plugs on

the  driving  side  of  the  crankcase  just  below  the
cylinder  base.  (On  no  account  must  these  plugs
be disturbed unless the driving side cylinder has
been  or  is  to  be  lifted  because  they  cannot  be
tightened without holding the nuts inside).

Access can now be obtained through the plug

holes to two screws holding the two halves of
the crankcase together which must be removed.

Remove three nuts in the timing chest, two

nuts on the driving side crankcase, two loose
studs through the bottom of the crankcase and
two loose studs through the back of the oil tank.

(The other studs have already been removed to
take the engine out of the frame.)

The two halves of the crankcase can now be

separated.

The inner race of the roller bearing on the

timing side will remain on the crankshaft
bringing with it the cage and rollers and leaving
the outer race fixed to the crankcase.

The inner race of the ball bearing on the

driving side is a tight fit on the shaft and can be
removed with special tool No. E.5121. If this is
not available, the shaft can be driven out with a
hide mallet or a soft metal drift.

To avoid damage to the ball bearing the case

should be heated to about 100°C. before doing
this.

4. Main Bearings

To remove the ball bearing from the driving

side crankcase, heat the crankcase to about 100°
C., by immersion in hot water or in an oven,
after which the bearing can be driven out using
a drift

which applies pressure to the outside

race only.

When fitting a new ball bearing, heat the

crankcase in the same way and use the same
drift, taking great care to keep the bearing
square with the bore.

To remove the outer roller race from the

timing side crankcase, first heat the crankcase,
then drive the race out using a small punch
through the three holes provided.

The inner race and rollers can be withdrawn

from the crankshaft using a claw-type extractor.

When refitting the inner race, drive it on to

the shaft until just flush with the end

and no

further.

5. Fitting the Connecting Rods.

To remove the connecting rods from the

crankshaft, first take out the cotter pins securing
the socket screws in the connecting rods and then
remove the socket screws themselves.

If the big end bearing caps are removed to

examine the condition of the bearings, make sure
that the caps are refitted the same way round on
the same rods and that the rods themselves are
refitted the same way round on the same crank
pins.

In refitting the connecting rods, the socket

screws should be tightened progressively with a
torque wrench set at 200-220 inch-lbs.

If the cotter pins do not come in line remove

the socket screws and use a different thickness
of washer. A difference of -005 in. in the washer
alters the position of the screw 1/8 of a turn.

There is a recess in one side of the connecting

rod for a cotter pin head and this side must face
outwards when the connecting rod is assembled
on the crankshaft to avoid fouling between the
cotter and the crankshaft web.

White-metalled steel liners are fitted in the

connecting rods and these are replaceable.

6. Re-assembly of the Crankcase

Fit the outer roller race in the timing side

crankcase, the ball bearing in the driving side
crankcase and the inner roller race on to the
crankshaft as described in Subsection 4.

Heat the timing side crankcase with the outer

roller bearing race in position to about 100°C.

Lay the crankcase flat on the bench and insert

the shaft, with the inner roller race in position,
arranging the connecting rods so that they do not
foul the crankcase.

Insert the camshafts in their correct position

(exhaust front, inlet rear) and see that the filter
housing is in position.

Put the distance piece in position on the