buell s1 lightning '97 Manual

See 

 The oil pump consists of two gerotor gear

sets, feed and scavenge (return), housed in one pump body.
The feed pump distributes oil to the engine, the scavenge
pump returns oil to the tank.

A gerotor-type gear set has two parts — an inner and an
outer gerotor. The inner gerotor has one less tooth than the
outer gerotor. Both gerotors have fixed centers which are off-
set to each other.

In a gerotor gear set, oil is transferred from inlet to outlet as it
is trapped between the rotating inner and outer gerotors. The
illustration below shows the principle of gerotor operation:

1.

During the first 180

°

 of rotation, the cavity between inner

and outer gerotors gradually increases in size until it
reaches its maximum size, equivalent to the full volume
of the “missing tooth.” The gradually enlarging cavity cre-
ates a vacuum into which oil flows from the inlet.

2.

During the next 180

°

 of rotation, the size of the cavity

decreases forcing oil into the outlet. See 

Gravity-fed oil from the oil tank enters the pump through
fitting (5). It is forced by gerotor set (7) through a hose to
the oil filter. Return oil from the flywheel compartment is
drawn back into the pump and is forced by gerotor set (9)
back to the oil tank.

See 

 for oil passages within

the engine.

The oil pump seldom needs servicing. Before you disassem-
ble an oil pump suspected of not producing adequate oil pres-
sure, be absolutely certain that all possible related
malfunctions have been eliminated:

1.

Make sure all oil hose clamps are tight and that hoses
are not pinched or damaged.

2.

Check oil level and condition of oil in tank. Pressure will
be affected if oil is diluted. In freezing weather, proper cir-
culation of oil can be affected if the oil feed hose
becomes clogged with ice and sludge.

3.

Check for a grounded oil pressure switch wire or faulty
switch if oil indicator light fails to go out with engine running.

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