2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 217Get this manual
ELECTRICAL 4Measure resistance between ground brush and brush plateResistance should be .3 ohms or less
Armature Testing
1Remove armature from starter casingNote order of shims on drive end for reassembly
Brush Inspection 1Measure length of each carbon brushReplace brush assembly when worn to 516" (8 mm) or lessThe brushes must slide freely in their holdersBrush Length 423Inspect surface of commutatorReplace if excessively worn or damagedUsing digital multitester, measure the resistance between each of the commutator segmentsThe reading should be .3 ohms or lessMeasure the resistance between each commutator segment and the armature shaftThe reading should be infinite (no continuity)
Limit 516" (8 mm) Brush Replacement 1Remove terminal nut with lock washer, flat washer, large phenolic washer, the small phenolic spacers, and sealing O-ringInspect O-ring and replace if damagedCheck commutator bars for discolorationBars discolored in pairs indicate shorted coils, requiring replacement of the starter motorPlace armature in growlerTurn growler on and position hacksaw blade or feeler gauge lengthwise 18" (.3 cm) above armature coil laminatesRotate armature 360 If hacksaw blade is drawn to armature on any pole, the armature is shorted and must be replaced