THE LUBRICATION SYSTEM
Fig. 1. Lubrication System
The engine lubrication system is of the dry sump type
operated by a double gear pump, situated in the
bottom of the crankcase on the right-hand side.
All oilways are internal except for the supply and
return pipes from the tank. The oil flows from the
tank to the supply pump (the top pair of gears) and
thence past the pressure valve (A) to the two oilways
feeding the cam spindles, and along the hollow
mainshaft to the big end bearing. After lubricating
the big end and circulating through the engine in the
form of a mist, the oil drains down through a filter in
the bottom of the crankcase, from which it is drawn
by the return pump (lower pair of gears) past ball
valve (C), and delivered up the return pipe to the
tank, where it passes through a fine mesh filter into
the tank itself.
Incorrect seating of the ball valve (A), will allow oil to
transfer from the tank to the engine, whilst the
machine is stationary. If the ball valve (C) should get
stuck in its seating, there will be no return of oil to the
tank. To check the oil circulation open the tank filler
cap and remove filter cap whilst the engine is
running. Oil should be seen issuing from the return
pipe from the crankcase. The tank and crankcase
should be drained every 2,000 miles and replenished
with clean oil.
Any restriction in the pressure release pipe in the
tank will cause an increase in pressure inside the oil
tank, and will result in leakage of oil at the filler cap.
This can be put right by inserting a length of flexible
wire into the pipe at its lower end (just in front of the
rear mudguard) and pushing the wire right up the
pipe, thus clearing any obstruction.
To remove the oil tank filter for cleaning, release the
tank filler cap, release the filter tap thus exposed, and
lift filter out. The filter should be placed in a can large
enough to cover it with petrol, and thoroughly
washed. Before replacing make sure that it is quite
dry of petrol.
The pump filter can be withdrawn after removing the
cover plate (B) and should be thoroughly washed
with petrol, dried and replaced.
NOTE. It is not advisable to remove the oil pump
unless the pump is definitely faulty.
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