5-3912345678910 ELECTRICALELECTRIC STARTING SYSTEMCHECKING THE ARMATURE COIL1. Check:• Commutator (outer surface)Dirty Clean it with #600 grit sandpaper.2. Measure:• Mica (insulation depth between the commutatorsegments)Out of specification Scrape the mica to theproper measurement using a hacksaw blade whichhas been grounded to fit the commutator.TIPThe mica insulation of the commutator must be undercut toensure proper operation of the commutator.3. Measure:• Armature coil (insulation/continuity)Defects Replace the starter motor.Connect the digital circuit tester to the armaturecoil.aDepth of insulator “a”:2.0 mm (0.79 in)Model 88 Multimeter with tachometer:YU-A1927Commutator continuity:ContinuityInsulation resistance:More than 1.0 M3121. Continuity check2. Insulation check3. Armature coil
