Royal Enfield 500 TWIN 1949 Workshop Maintenance Manual page 16

ROYAL ENFIELD WORKSHOP MANUAL
Remove the oil pipe connection and plug
from the cylinder head and the rocker spindle
can then generally be withdrawn by means of a
piece of rod inserted in the central hole.
If this is not successful remove the oil pipe
plug on the opposite cylinder head and the two
plugs between the heads and drive the rocker
spindle out with a piece of rod passing through
the rocker spindle in the opposite cylinder head.
On re-assembling, make sure that the spring
washers are fitted on the insides of the rockers
and the plain thrust washers on the outer sides.
13. Removal of Valve Guides
To remove the valve guides from the heads
two special tools are required which can easily
be made.
The first is a piece of tube with an internal
bore of not less than 7/8 in.
The second is a mandrel about 4 in. long,
made from 9/16 in. diameter bar with the end
turned down to about 5/16 in. diameter for 1/2
in.
Support the cylinder head on the tube which
fits over the collar of the valve guide. Using the
mandrel force the guide out of the head with a
hand press or by using a hammer.
To fit a new guide, support the head at the
correct angle and use a hand press and the same
mandrel. If a hand press is not available and the
guide is replaced by a hammer, use a piece of
tube of 9/16 in. internal diameter to prevent
damage to the bore of the guide. It is necessary
to re-cut the valve seat and grind in the valve
after a guide has been replaced.
14. Renewal of Sparking Plug Inserts
A steel thread insert is fitted into each
sparking plug bore to prevent damage to the
threads in the alloy cylinder heads.
This insert should not normally require
renewal but if it does become damaged, for
instance by a faulty plug, it can be pulled out
with a pair of pliers and a new one fitted.
To fit a new insert a special tool consisting of
a piece of 7/16 in. diameter tube or rod with a
slot cut in the end is required.
The new insert is placed over the tool with
the tag engaging in the slot and it is screwed into
the plug hole in the cylinder head from the
outside until the last coil is 1 to 1.1/2 threads
below the top face. A reverse twist of the tool
will then break off the tag.
If the cylinder head has not been removed
from the engine, care must be taken not to drop
the end of the tag into the cylinder and in such a
case it is better to break off the tag with a pair of
long nosed pliers.
15. Removal of Cylinders
When the cylinder heads have been removed
the cylinders can be lifted clear off the studs.
Section C1 Page 5