TM 55-4920-384-13&P
The flywheel is marked with the letters `DC' near
tion cable from the spark plug and holding the ter-
one of the air circulating vanes. This vane is further
minal 1/8 inch away from the air shroud or any other
metal part of the engine, as shown in Fig. 13. Turn
identified by an `X' mark cast on the end. See Fig.
the engine over slowly by the starting crank two com-
hole, continue turning the starting crank until the
plete revolutions and watch for the spark discharge
edge of the marked vane on flywheel is on line with
which should occur during the cycle, at the instant
the mark on the vertical centerline of the shroud as
the impulse coupling on the magneto snaps. Repeat
shown on Fig. 14. Leave flywheel in this position;
this check with each of the other ignition cables. If
At this point the keyway for mounting the flywheel is
there is a weak spark, or none at all, check breaker
also on top.
point opening as mentioned in preceding paragraph
under "Magneto Breaker Point Adjustment". If this
Next, remove fitting from inspection hole, located in
does not remedy the trouble, it may be necessary to
the gear cover at the magneto mounting flange, as
install a new condenser. See Magneto Manufacturer's
shown in Fig. 14.
Maintenance Instructions in the rear of this manual.
Assuming that the magneto has been removed from
the engine, the following procedure should be follow-
MAGNETO TIMING
ed before replacing magneto:
The magneto is properly timed to the engine at the
The Number 1 cylinder firing position of the magneto
factory, but if for any reason it is necessary to retime
must he determined; Insert the ignition cable into the
the magneto, it can be done in the following manner
No. 1 tower terminal of the magneto end cap and hold
First remove the screen over the flywheel air intake
the spark plug terminal at the other end, about 1/8"
opening by taking out the screws holding the screen
away from the magneto body. Turn the magneto gear
in place. This will expose the timing marks on fly-
in a clockwise rotation, tripping the impulse coupling
wheel and shroud. See Fig. 14.
until the No. 1 terminal sparks then hold the gear in
Next, remove the spark plug from No. 1 cylinder and
this position. Mount the magneto to the engine, mesh-
ing the gears so that when the magneto is in place,
turn the engine over slowly by the starting crank, at
the same time holding a finger over the spark plug
the gear tooth marked with an `X' will be visible
through the lower half of the inspection hole in the
hole, so that the compression stroke can be deter-
mined by the air blowing out of the hole.
gear covet. See Timing Diagram, Fig. 14. Tighten the
D-13
