Slight disagreement with this - A short in the starter motor windings will cause an excess current which in turn will cause the wires to get warm (and also blow the fuse - hopefully before a fire starts). A 'bad earth' i.e. a high resistance earth connection will add resistance to the circuit thus lowering the current through the wires. Any 'bad connection' will cause this. If the starter motor is OK and the solenoid OK and the earth (ground) connections/plugs/sockets all ok, then I would look for a trapped or chaffed cable that is 'shorting' which would cause the symptoms described. The easiest way to check for a cable and/or earth fault is as follows: 1. Disconnect and remove (or isolate) the battery. 2. Disconnect the main (thick wire) feed to the starter motor. 3. Connect a car battery (using 'jump' leads) to the disconnected terminal of the starter motor and the frame (mounting bolt). if the starter motor turns over OK, then suspect wiring / solenoid. 4. Remove 'jump' leads and re-connect the starter motor and disconnect the main (thick) wire to the solenoid. 5. Completely isolate the wire disconnected in 4 above (use insulation tape). 6. Reconnect the bike battery. 7. Connect the car battery (using jump leads) to the Solenoid connection and the earth (frame bolt). 8. Turn on ignition and press 'start'. If the starter motor turns OK, then you have a bad connection between the bike battery and the solenoid. if the motor does not turn, then either the Solenoid is caphooey or a starter circuit wiring fault. 9. Ignition off - run a wire from the bike battery to the small terminal on the starter solendoid. if the starter motor turns, then ignition wiring fault. if not, solenoid is faulty. Good luck.