Starer motor?
 

My 2009 F650GS Twin would barely turn over. I replaced the battery with Shorai Lithium, and starting is better but not 100%. Alternator is functioning properly, but bike is acting like starter motor is weak. Bike only has 7000 miles.
How the heck can I diagnose the starter motor?
Thanks ahead of time...

You say that the charging system is good. By what means did you determine this.?? At 7000 miles your starter should be fine, and they have known to have charging issues.

Try hooking up to another battery to jump the shorai and see if the starter works normally.
If it still does not crank start checking for a wiring issue ( loose connection to ground ).
These starter motors are very dependable and their are very few reported issues of motor problems.