When does this single click from solenoid occur,could be a number of things causing it to not spin the starter one could be battery related and not enough power to turn the starter motor, if it is when bike has not been used for while would look towards battery condition, using a multi-meter to measure state of the battery and see also what it reads with engine running so you know it is getting charged from the alternator, otherwise could be a bad contact in the solenoid, a sticking starter motor usually gives a humming or slight buzzing noize from the starter motor to point you to that if it was playing up...test your battery state when it does a single click first.