I have just purchased a k100 It has a problem in that the neutral light stays on . All gear numbers are displayed when riding. Im not too smart with electrics however I have removed the switch from behind the swingarm and cleaned it several times No change.What next???

Possible that the gear indicator circuit card in the OEM gauge is broken.  Run the following test.
1. Temporarily disconnect the clutch switch from the harness
2. Turn on the Ignition.  Put the bike in first gear
3. Measure the voltage on Pin 5 (Black/Green) on the cable connected to the back of the OEM cluster.

If you measure 10V or more, then it's a sure sign the GPI board is defective.

robmack wrote:Possible that the gear indicator circuit card in the OEM gauge is broken.  Run the following test.
1. Temporarily disconnect the clutch switch from the harness
2. Turn on the Ignition.  Put the bike in first gear
3. Measure the voltage on Pin 5 (Black/Green) on the cable connected to the back of the OEM cluster.

If you measure 10V or more, then it's a sure sign the GPI board is defective.

Even if the clutch switch is shorting then that still shouldn't illuminate the neutral lamp. 

If things worked that way then the N lamp would illuminate every time that you pull in the clutch to shift gears.

If the gear indicator shows something other than zero and that lamp is on then it's a GPI circuit board gone bad.

Thanks for the response Will annoy my brother now as he has more electrical knowhow than me plus he has had his instrument cluster apart before.

How to replace GPI PCB at this link:

https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/gpi/gpi.htm#replace

duck wrote:
Even if the clutch switch is shorting then that still shouldn't illuminate the neutral lamp. 

I don't suspect the clutch switch as the culprit in this scenario, Duck.  I suspect the GPI board also; specifically the neutral and start enable transistors. I had the first step being taking that switch out of circuit to reduce the number of variables during testing.

Another quick test is to put the bike on the centre stand, turn on the ignition, put it in first and press the start button.  If the starter cranks, then the GPI board is defective.