neutral light troubleshooting

[bluesman]

Hello all,
I just returned from a short ride and when I pulled into the barn the neutral light wasn't coming on. It is a '79 r100. The bike will start with the clutch pulled in but not without. My question is, is it possible that the bulb being burned out could cause this?

Thank you,
Bluesman

[RPGR90s]

the bulb needs to light for the engine to start without the clutch lever being pulled in.

An easy check is to remove the two wires from the neutral switch and short them together and turn on the ignition.

If it lights, the problem is in the switch.

If it doesn't light, it's probably the bulb. I emphasize probably as it could be the bulb contacts, bulb holder, instrument cluster connector (that big rubber square that plugs into the instrument cluster).

[bluesman]

Thank you, I have the instrument cluster apart now cleaning contacts.

[Kurt in S.A.]

Be careful cleaning the inside of the housing. The circuit consists of delicate foil and it can be torn. I don't believe they are sold anymore but one can upgrade to an LED set up from Katdash.

https://katdash.com/

Kurt in S.A.

[bluesman]

Thanks for the link!

[bluesman]

Ok, cleaning the contacts did the trick. also the screw that holds the plug was missing. So probably a combination of the two. Thanks everyone for their input.

[SteveD]

The screw that holds that big Wurth plug in place isn't critical as long as the plug is pushed in all the way. Mine hasn't had that screw for over a decade. I smear some rubber grease on the edges to make it easier to remove.

Years back, on another bike, my circuit board copper foil connectors were dodgy. I just placed a small strip of double folded aluminium foil underneath the cracked ones and it then worked fine.