Starter problems can be caused by:
1. bad starter
2. bad solenoid
3. bad starter button
4. bad wiring
5. starter gear not shimmed right
Since any of these are about as likely as any other, you can do this stuff in no particular order:
1. test starter: Take it out and connect a ground to the starter case... touch a wire to the lug that has the nut on it where your cable connects to a POS battery pole. If the starter spins, it is OK. If it doesn't replace or check the brushes... I think you can buy a brush kit
2. test solenoid. Connect the clip of a trouble light to the lug on the solenoid you originally had your starter connected to. Connect the other lug to your battery. Take a wire and connect to the POS anode on your battery and touch it to the solder joint where the small gauge black wire is connected on the solenoid. If the test light comes on the solenoid is OK. If the starter is back in the bike, it will crank when you touch a positive voltage to the black wire connection.
3. starter button test: Turn the key on. Pull in the clutch lever. There is an interlock switch on the clutch lever where the power goes through it and gets back to where it feeds into the button. (you need an extra set of hands for this stuff)... With key on and clutch lever pulled in, see if power is getting TO the button. That is, open switch gear and put the POS probe of a multimeter in VDC scale on the black wire inside the switch gear where it goes into the button. There should be power there. If there isn't you will need to investigate the clutch interlock switch. You can replace it or make sure that the plunger on the switch and lever make good contact and the plunger moves freely (some spray oil can help) or replace the switch if you can get it to work. If you DO have power at the point where the black wire goes to the button, move the probe to the other side of the button to the wire OUT of the button (where it connects to the main harness) and push the button on with the clutch lever pulled and the key on (and the kill switch in the RUN position). If you get power there at the connector to the main harness, the button is OK... if not, poke around and find out why not. The contacts on button are usually the culprit and these can be replaced. Z1Enterprises.com sells the buttons/contacts I think.
4. bad wiring check - this is usually the interlock getting disconnected or perhaps the switch itself. You can check voltage in and out of the switch easily with a multimeter. Remember this voltage is switched (key ON) and that it goes through the kill switch.
5. starter gear shimmed properly... this problem usually shows up when the starter actually spins but doesn't engage the starter gear regularly. Kaw lists three shims that go under the starter gear to space it OUT correctly so it can contact the gear on the starter itself. Having a problem with this normally occurs only when swapping starter gears.
