Greetings,
With respect incase you or others might not understand the system, most bikes basically have three starter isolator methods to try and stop folks starting their engines when they perhaps should not, however because the switches sometimes fail or get water logged many riders, especially trail riders, remove them.
The switches typically are found on;
1. the side-stand which prevents riders inadvertently moving off with the stand down, ready to catch the road when turning and throwing the rider off - a form of nature's natural selection process
2. there could be a small switch located into the handlebar clutch lever perch, this prevents the starter being engaged when a gear has been selected and whilst the clutch is also engaged to provide drive from the engine to the gearbox. So, by pulling in the clutch control lever you could, without the need of having to find neutral, quickly start the engine if it had stalled
Attachment:
lever switch.jpg [ 26.44 KiB | Viewed 17968 times ]
3. plus one neutral light switch on the gearbox, this one typically earths out a neutral light circuit simply to indicate that the gearbox is in neutral, but also it might prevent the starter from being engaged when in gear on more complex systems
The gearbox might be further complicated by an actual larger switch which tells the engine control unit, ECU, which gear has been selected so that the onboard electronics can adjust ignition timing and fuelling, especially on petrol injection models.
If all that you want is a neutral 'light' then if the original wiring has been modified by a previous owner you may need to make up a simple auxiliary circuit consisting of an ignition only fed 12v live feed; an inline 2amp fuse which connects to an led bulb and holder, lead from the bulb connects to an neutral light switch typically found near to the gearbox drive sprocket. The switch may have been disconnected but it will undoubtedly still be in place.
Attachment:
drz400 neutral switch.jpg [ 34.91 KiB | Viewed 17968 times ]
I hope that these comments help you but please do not hesitate to ask should you need further details and one of us will get back to you
TTFN
Hugh.