Royal Enfield 500 TWIN 1949, Workshop Maintenance Manual

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ROYAL ENFIELD WORKSHOP MANUAL
to damage but, if they should become damaged,
the same wire insert that is used in the crankcase
can be fitted by cutting a thread with a special
tap.
The method of fitting the thread inserts is the
same as that used for the sparking plug inserts
described in Subsection 14.
" 500 Twin." The oil pipe bosses on the "500
Twin" are on the base of the cylinder barrels and
not on the crankcase and wire inserts are not
therefore necessary.
33. Pressure Relief Valves
There are two pressure relief valves in the oil
feeds to the big ends and to the rocker gear
respectively. Their function is to prevent
excessive pressure and their setting is not
critical.
They are set before leaving the Works and
should not normally require to be disturbed. If,
however, it is found necessary to dismantle
either of them, they can be reset as follows:
Rocker Feed Relief Valve. This is located in
the crankcase face behind the timing cover and
consists of a 3/16 in. diameter steel ball held in
position by a spring and brass plug. If the plug is
screwed in until it is flush with the face of the
crankcase, the pressure will be relieved at
approximately l0 lbs. per square inch. The plug
is prevented from moving by peening over the
aluminium into the screwdriver slot with a small
centre punch.
Big End Feed Relief Valve. This is located
in the inside of the bottom of the timing cover
and consists of a 1/4 in. diameter steel ball and a
spring and plug. It should be set to relieve the
pressure at approximately 60 lbs. per square
inch.
The pressure can be measured by applying an
air line with a pressure gauge (or a suitable force
feed oil gun) to the oil feed plug in the timing
cover which fits into the pump worm.
Rotate the pump spindle by means of a
screwdriver until the ports are sealed by the
pump disc. The ports are sealed when no
leakage occurs on the timing cover face.
Turn the relief valve plug until the pressure
at which the valve opens is about 60 lbs. per
square inch, then secure the plug by peening as
above.
If too high a pressure is applied, the pump
disc will be forced off its seating.
On earlier models the pressure relief valve
for the oil supply to the big ends was in the
crankshaft. Some trouble may be caused by dirt
under the ball causing the valve to stick. If so
desired, the relief valve can be removed and the
oil passage blanked off and the new type of
timing cover fitted.
Section C1 Page 9
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