1998-2001 Yamaha YFM600FHM Grizzly Factory Service Manual, Page 317Get this manual
ELECTRIC STARTING SYSTEM
IELEC I0 I
STARTER MOTOR INSPECTION 1.1nspect: Commutator Clean it with #600 grit sandpaperDirty 2.Measure: Commutator diameter Out of specification Replace the motorOutside diameter: 28 mm (1.10 in) Wear limit: 27 mm (1.06 in 3.Measure: Mica undercut E Out of specification Scrape the mica using hacksaw bladeMica undercut: 0.7 mm (0.028 in) NOTE: _ Scrape the mica to the proper measurement using hacksaw blade which has been grounded to fit the commutator