Under a HIGH-speed condition, the throttle
body is opened up all the way, allowing
maximum airflow. This creates the greatest
vacuum pressure possible, resulting in
maximum fuel spray from the main jet. The
air/fuel mixture becomes richer to facilitate
the faster, hotter combustion necessary to
support the increased engine speed and
demand.
LUBRICATION SYSTEM
The engine’s lubrication system has several functions:
Lubrication
Heat Dissipation
Cleansing/Rinsing
Intermediary Seal
Protect Against Wear
PROCESS
The engine’s oil pump (located in the RH crankcase) is gear-driven by the crankshaft
directly. Oil is drawn from the reservoir to the carburetor via the pump, where it is injected
into the air/fuel mix.
Due to the intake process of the two-stroke engine (see The 2-Stroke engine Cycle), the oil
most effectively lubricates the crankcase by combining with the air/fuel charge, getting
spread throughout by the rotation of the crankshaft. Since two-strokes are typically air-
cooled and therefore operate at a much higher temperature, the oil also further lubricates as
well as acts as an intermediary seal within the combustion chamber. As it burns, the oil also
has a cleaning effect, taking with it any significant carbon buildup. (Refer to THE 2-
STROKE ENGINE CYCLE for illustrations/further description)
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