Figure 3-17. Magneto

TM 5-4110-217-14

Figure 3-18. Ignition Timing

Either spark plug can be used as they fire

Screw

simultaneously.

Washer

(2) Place a white chalk or paint mark on the

Spacer

Clip

timing mark.

Magnet

Screw

(3) Start the engine and check the timing.

Magneto stator assembly

Correct timing is 19 BTC.

(4)

If timing

needs adjustment, loosen the mounting screws on

Figure 3-17. Magneto

breaker box and move it left to advance or right to retard

the timing.

d. Rotate engine clockwise (facing flywheel) by

(5) Tighten the screws on the breaker box

hand until points are fully open. Turn screw (C) until

and recheck timing.

point gap measures 0.020 inch; use flat thickness

(6) Replace breaker box cover and any other

measuring gage.

hardware removed.

e. Tighten mounting screws and recheck gap.

b. Engine Not Running.

Replace both spark plugs.

(1) Connect a continuity test lamp set across

the ignition breaker points. Touch one test prod to the

NOTE

breaker box terminal to which the coil lead is connected

and touch the other test prod to a good ground on the

If spark plugs have not been changed

engine.

within 200 hours of operation, replace

(2) Turn

crankshaft

against

rotation

them with new ones after setting breaker

(counterclockwise) until the points close. Then slowly

points.

turn the crankshaft with rotation (clockwise).

(3) The lamp should go out just as the points

g. Proceed to ignition timing.

break.

(4) If timing needs adjustment, loosen the

3-45.

Ignition Timing.

mounting screws on breaker box and move it left to

a. Engine Running Timing. Always check timing

advance or right to retard the timing.

after replacing ignition points or if noticing poor engine

performance. Proceed as follows:

3-46.

Alternator.

(1) To accurately check the ignition timing,

The alternator (fig. 3-19) covered in this paragraph

using timing light when engine is running. Connect the

is designed for 12 volt negative ground electrical

timing light according to manufacturer's instructions.

systems. The mechanical construction of the alternator

differs from the DC generator in that

Change 3 3-25