2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 212Get this manual
Electrical systems 2Measure the commutator diameterReplace the armature if below specification
Disassembling the starter motor
1Slide the pinion stopper down as shown, and then remove the clip 2
NOTE: Remove the clip with thin screwdriver2Remove the bolts, and then disassemble the starter motor
Commutator diameter wear limit: 28.0 mm (1.10 in) 3Measure the commutator undercut aReplace the armature if below specification