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 TM 5-2805-261-13
Notice in Diagram G that the two flywheel magnets are
mounted into the rim of the flywheel with their magnetic polarity
3.
The manualstarter engages the power head
reversed from each other. As the flywheel spins past the trigger
flywheel ratchet with three pawls when the
coil, the S-pole of one magnet passes the coil first and the N-
starter rope handle is pulled. A coil spring is
pole of the other magnet passes first. The result of this polarity
wound as the rope unwinds and unwinds as the
difference is that the electrical pulse generated in the trigger coil
handle is returned to the starter housing.
is positive in one instance and negative in the other. Inside the
power pack of this 2-cylinder engine, there are two SCR's.
This starter has a high speed interlock which prevents the
Each is connected to a different ignition coil. The SCR's are set
starter from operating if the throttle is in the "FAST" position.
up so that one of them triggers on a positive pulse and the other
on a negative pulse. In this way, the two spark plugs are
alternately fired to provide proper engine timing.
2.
The sparkplug must satisfy two engine
requirements.
It must hold cylinder
compressions ... and it must provide a spark of
sufficient intensity to insure full explosion of the
combustible fuel-air mixture compressed in the
cylinder by piston action.
The first requirement is fulfilled only when the threaded reach of
the spark plug is fully tightened in the cylinder head. The
degree of tightening is determined by the amount of torque
specified by the manufacturer. A gasket is also employed to
insure correct plug setting. A loosely installed spark plug will
overheat and eventually become badly burned. Insufficient
spark plug torque is responsible for a large number of engine
troubles.
Fulfillment of the second requirement, fuel mixture ignition, is
accomplished only when the correct spark plug is in satisfactory
operating condition. Spark intensity is affected by fouled or
burned electrode tips, cracked insulator porcelain, and by faulty
high tension lead connection. Spark intensity can also be
reduced by faulty operation of other component parts in the
ignition system.
Figure 1-19. View of rewind starter
D. LOWER UNIT. Includes the exhaust housing and gear
case. The exhaust housing is basically an extension of
the powerhead to the water. It contains the shift lever,
upper shift rod, drive shaft, and channels for the
exhaust and cooling system. The gear case transfers
the power from the drive shaft and powerhead to the
propeller. It transfers this power by engaging two level
shaft. The gear case also contains the cooling water
inlet and the cooling water pump.
Figure 1-18. Spark plug
1-10
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