Motorcycle Questions? Ask a Mechanic.
It sounds like your starter solenoid contacts may be the issue. Over time they degrade and limit the amperage that can pass through them. There is a check to do prior to opening up the solenoid.
You'll want to make a jumper wire out of a heavy gauge wire (12 or bigger). Remove the green wire from the solenoid. With the bike in neutral connect the jumper wire between the positive battery terminal (or large terminal on the solenoid) to the terminal that you removed the green wire from. If the starter works reliably by doing this you have a weak starter relay circuit. You'll need to troubleshoot through this circuit to determine where the weak point is.
If the starter still gives you the clicking sound and doesn't work reliably then you have a solenoid contact issue. You access these by removing the 3 solenoid end cover bolts and pulling out on the cover.
I hope this helps. Please let me know if I can be of further assistance. Also, please leave a positive rating for my service today. Thanks, P.J.