Checking the clutch safety switch

The first thing to check is the sound. When the clutch (or brake) lever is squeezed, the switch moves. The Kawasaki switches have a 'click' at the transition between off and on. Squeeze the brake a couple of times to listen for the 'click', then go to the clutch side and listen for the same noise.

If this checks out, do the following:

Put bike in first gear with the engine off and sidestand up. Pull in clutch lever. Try to start bike. Bike should crank over. Shut engine off. Release clutch lever. Try to start bike.

If the clutch switch is good, the engine will not crank over. If the switch is bad, the bike will start cranking, chugging you forward.

If you are able to hold the clutch lever in while the engine is running, but, as soon as you start to release the lever, the engine turns off, that means it's the sidestand switch and not the clutch lever switch.

If it won't go into first with the sidestand down, regardless of the position of the clutch, chances are pretty good that the clutch safety switch is not working properly. If you have ever taken the lever off, chances are you broke the plastic plunger (see below).

If not, the switch is most likely bad. The bike won't start at all if the wiring harness is completely disconnected from the lever.

Testing the switch should take all of ten minutes with an ohmmeter. Here's how to go about that:

Physical: locate the switch. It's under the clutch lever. Examine it. If it has a black plunger sticking out of it which touches the hangy part of the lever (most visible when the lever is not pulled), the plunger is not broken.

Testing for switch function: follow the wires out of the switch to where they meet the wiring harness. Unplug the wiring harness. Take an ohmmeter (i.e... a multimeter set to "ohms", lowest range available if it is not auto-ranging) and stick the meter's probes into the middle and the left holes in the switch's plug. Pull and release the lever. The readout on the meter should change; in one position, it should be close to 0 ohms, in another position, it will be infinite. On an analog meter, 0 ohms is usually all the way to the right and infinite all the way to the left. On a digital meter, 0 is pretty obvious, infinite is usually something cryptic like "-0L" (consult meter manual for specifics). Now, test the middle and the right contacts. The behaviour should be the exact opposite.

If you don't get these readings, you may need to either clean or replace your clutch switch.