Royal Enfield 500 TWIN 1949 Workshop Maintenance Manual page 10

ROYAL ENFIELD WORKSHOP MANUAL
On earlier engines the ignition is provided by
a coil energised from the battery and a
distributor mounted above the dynamo. The
dynamo is driven at engine speed by a chain
from the rear camshaft.
14. Carburettor
"Meteor" Amal Type 276 FJ/IAT.
"500 Twin" Amal Type 276 DU/IAT.
Left hand throttle stop and pilot adjuster.
Standard bottom-feed float chamber, cranked
at 7°.
Bore: "Meteor 700," 1.1/16 in.
"500 Twin,"
The correct settings are as follows:
Main Jet ............. No. 170
Needle Jet .......... No. 106
Throttle Valve
Needle Clip
15. Air Filter
The air filter is a Vokes Micro-Vee felt and
gauze dry filter, 5 in. diameter. It is housed in a
metal box bolted to the frame.
16. Lubrication System
Lubrication is
Dry-Sump system which is entirely automatic
and positive in action. The oil tank is integral
with the crankcase, ensuring the full rate of
circulation immediately the engine is started and
rapid heating of the oil in cold weather.
There are two positively driven piston type
oil pumps running at 1/6 engine speed,* one at
the rear of the timing cover for pumping oil to
the bearings under pressure and the other at the
front for returning the oil from the crankcase to
the tank. The return pump has a capacity
approximately double that of the feed pump
which ensures that oil does not accumulate in the
crankcase.
The oil from the big ends drains into the
bottom of the crankcase through a gauze which
prevents it being drawn up by the flywheel. On
some models the gauze is replaced by a steel
deflector plate.
The oil from the rocker bearings is squirted
through a small hole in the rocker on to the top
end of the push rod. It flows down the push rod
into the cam tunnel where it lubricates the cams
and tappets and thence into the timing chest,
lubricating the timing chains. There are small
holes from the cam tunnels through the cylinder
walls for the purpose of lubricating the skirts of
the pistons.
*1/12 engine speed on early models. ** Early "500 Twins" had internal passages leading to the rocker gear.
15/16 in.
" Meteor " " 500 Twin "
No. 150
No. 109
6/4 6/4
Middle No. 2
Groove Groove
by the Royal Enfield
Both pumps are double acting, one side of the
feed pump supplying the big ends only and the
other side the rockers and valve gear. In a
similar manner one side of the return pump
pumps the big end oil back to the tank from the
crankcase and the other side the valve gear oil
back to the tank from the timing chest.
Separate adjustable spring loaded relief
valves control the pressure to the big ends and to
the valve gear. The oil supply to the big ends is
through internally drilled passages, and that to
the valve gear through external pipes.** On later
models the oil filter is in the oil feed to the big
ends instead of the return circuit and is located in
the bottom of the timing cover instead of in the
oil tank.
17. Breather
The efficient operation of the breather is of
paramount importance to the performance of the
engine as it acts as a non-return valve between
the crankcase and the outside atmosphere,
causing a partial vacuum in the crankcase and
rocker boxes which prevents the passage of oil
into the cylinder and consequent smoking and
oiling of the plugs.
The breather is located on the driving side of
the crankcase and consists of a small housing
containing two small pen-steel discs covering
two holes drilled in the crankcase. Accurate
seating of the discs is ensured by a pensteel plate
held between the breather body and the
crankcase. On early models the breather is in the
end of the crankshaft.
18. Gearbox
The gearbox is bolted on to the back of the
crankcase and has four speeds, which are foot
controlled, and a patented neutral finder. All
gears are in constant mesh, changes being
effected by robust dog clutches.
The standard gear ratios are as follows:
" 500 Twin " (solo). 5, 6.5, 9, 13.9:1
" Meteor " (solo). 4.47, 5.8, 8.05, 12.4:1
"Meteor"(sidecar). 5.03, 6.53, 9.05, 13.95:1
19. Clutch
"Meteor" Engine. The clutch has six pressure
plates and five friction plates, including the
sprocket which is lined on both sides with
friction material. The other friction plates have
cork or Klinger inserts which give smooth
operation and freedom from slipping in the
presence of oil. The clutch centre is fitted with
shock absorbers consisting of rubber blocks.
" 500 Twin" Engine. The clutch is similar to
that on the " Meteor" engine except that there
are five pressure plates and four friction plates
and the clutch centre is solid.
Section B1 Page 3