c.
Replace distributor gear if worn, cracked, or chipped.
5.
Inspect high tension lead from coil to make sure it makes contact with carbon brush on distributor gear shaft.
6.
Check the condenser for looseness, dirt, and damage. If dirty, remove and clean lightly with soapy water. dry thoroughly. Using a condenser tester check for capacitance (0.35 microfarads, ±10 percent), series resistance and leakage. Resistance between the condenser lead wire and condenser shell should be greater than 10 megaohms.
7.
Inspect impulse coupling every 500 hours. Inspect impulse coupling shell and hub for cracks, rust, corrosion or damage. Inspect impulse coupling pawls for loose rivets, rounded, peened, or excessively worn pawls. If any of these conditions are evident, impulse coupling must be replaced.
8.
Check action of impulse coupling. With the ignition switch off, observe breaker cam end of rotor while manually cranking the engine through a firing sequence. The rotor should alternately stop and then (with an audible snap) be rotated rapidly through a retard firing position. If impulse action is not correct, remove magneto for overhaul.
9.
Look for frayed insulation or broken wire strands in leads at back of magnetos. Check terminals are secure and properly positioned.
10.
Check the lead conduits. A few broken strands are acceptable, but if the insulation is deteriorated, replace it. Special high temperature coating, used on harness is provided for vibration resistance and mechanical protection. Harness integrity is not sacrificed if small areas of the braid show peeling or flaking of this coating.
11.
Check springs for breaks, corrosion, or deformation. Check continuity from block with tester or light.
12.
Check insulators for cracks, breaks, or evidence of aging. Be sure they are clean.
13.
Check ventilator plug. Ensure vent holes are clean and free of obstructions.
74-10-00 Page 74-8 Revised: February 28, 2002
3H12
74-10-00 Page 74-9 Revised: February 28, 2002
MAGNETO OVERHAUL INSTRUCTIONS.
DISASSEMBLY OF MAGNETOS. (REFER TO FIGURE 74-4.)
— Note —
The slick T-100 Assembly and Timing Kit is strongly recommended. The tools in this kit will greatly aid magneto disassembly/assembly and help prevent damage to parts.
1.
Remove cotter pin, nut, washer, and gear. Grasp shell of impulse coupling assembly and gently pull assembly outward to clear latching ears.
2.
Allow shell to turn, cautiously releasing spring tension, and withdraw shell and coil spring. Using slick puller T-106 in the grooves on impulse hub, pull assembly off shaft taper and discard. Remove key.
3.
Remove four screws and four washers. Separate distributor housing and disconnect condenser lead at contact breaker assembly.
4.
Remove two screws and two washers. Withdraw and discard bearing bar, distributor gear, and distributor block from distributor housing.
5.
Remove condenser taking care not to twist lead wire.
6.
Using two flat blade screwdrivers or equivalent, placed under rotor gear, gently pry gear off rotor shaft and discard.
7.
Remove and discard breaker assembly by disconnecting coil lead wire and removing screw and washer. Remove cam by prying straight up with a screwdriver blade and discard.
8.
Remove two screws, two washers, and two bearing plate clamps. Press against drive end of rotor shaft and withdraw bearing cap assembly, rotor, and ball bearing from magnetoc frame. Place rotating magnet in a suitable keeper and press ball bearings off journals. Discard ball bearings and washer.
9.
Using coil wedge extractor T-122, remove coil wedges, lift out, and discard coil. (Refer to Figure 74-3.) Remove air vent and tachometer magnetic sensor. Remove and discard oil seal.
74-10-00 Page 74-10 Revised: February 28, 2002
3H14
Figure 74-4. Exploded View of 4300 Series Magneto
3H15 74-10-00 Page 74-11 Issued: April 1, 1997
CLEANING AND INSPECTION OF MAGNETOS
1.
Inspect internal and external threads of all threaded hardware. Damaged or worn parts must be replaced.
2.
Inspect bearing cap assembly for excessive wear and damage. If rotor shaft binds, sticks, or is loose in bearing cap, replace bearing cap assembly.
3.
Check rotor for damaged or worn key way. Check rotor bearing surfaces for excessive wear. Inspect rotor shaft for dimples from impulse coupling. Replace if more than .006 inch per side.
4.
Inspect magneto frame and distributor housing for cracks or other damage.
5.
Clean all parts thoroughly with grease solvent before assembly.
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