Motorcycle Repair: starter problem, starter clutch, carbon brushes

Question
Hi Mark
1990 CBR1000FL (26K miles)
Starter will not spin engine fast enough to start it. Have stripped and tested starter with meter - all ok. Have borrowed 2 starters from a breaker - no improvement. Have gone direct to starter motor with jump leads from car (thus eliminating bike electrics as a problem)- no improvement. Engine turns freely with a spanner and valve timing etc are ok.
This problem has reared its head on and off over the last couple of years, but engine has always eventually started. Now it will not.
I fear it may be the starter clutch, but I don't understand how this can cause engine to turn slowly.
Any tips will be much appreciated
Thanks
Tony


Answer
Hi Tony,

I would need to perform a few checks to determine the exact cause. The starter motor needs to be disassembled and the carbon brushes inspected. Clean any carb powder build up. Check resistance between comutator segments.

Visit this website and learn about the starter clutch:

www.netcrafting.com/motorcycles/starter_clutch_files/starterclutch.htm

Respectfully,
Mark Shively