Headlight

[545863]

I've had a problem with the headlight on my CB100N which I traced to the handlebar switch, after cleaning the switch it worked for a short while but is now dead again. I was thinking of wiring up the headlight so that it comes on permanently when the ignition is switched on. I assume that it will have to be on dip permanently but this is not a problem as I only ride the bike during the day. I want a working headlight during the day as this is how I normally ride the bike anyway. Is it as simple as joining wires together to achieve this? If so, which wires? Cheers.

[McCabe-Thiele (Ted)]

Personally I would try the cleaning fix again after testing for power to the bulb holder in case it's a poor contact. Then start searching for a replacement part.
In addition if you have not already done so I would fit an LED headlamp bulb to cut power consumption.

[Oddjob]

If you join 2 wires together how are you going to select main beam? you may never need it but it will fail an MOT if it doesn't work.

Most likely a faulty wire in the headlight switch or a broken contact plate, fix it again or buy a new switch is my advice.

The 100N never had a good charging circuit, running with the lights on is ok but if they were permanently on and you ran into a problem you'd not get the bike home, if you can switch the lights off at least you can save power when it's needed and of course if it started to blow fuses and the lights were at fault you'd struggle to isolate the offending part.

Modern bikes have a circuit where when the bikes trying to start the headlight goes out, this is to allow the engine the maximum power in the battery so it can start.

[545863]

Thanks for your advice. MOT is not an issue as the bike is registered as historic and therefore exempt, (I imagine it's probably illegal though)! I've been searching for months for a replacement switch unit but the right hand switches do not seem to come up for sale, there are loads of left hand switches about, any right hand switches that I have seen on ebay have not been the correct ones. The OFF>ON switch appears to be the problem not the beam selector switch, maybe I could wire in a toggle switch as the on-off switch instead of at the handlebars?

[Oddjob]

Oddly CMS do not list the CB100N, they do show a CB125N 1980 though which is around the same time.

Does the switch look like this?

https://www.cmsnl.com/honda-cb125t-1980-a-england_model16544/swassy-ltdim_35150399780/

If not do you know the part number?

This is on Ebay

https://www.ebay.co.uk/itm/364208264027?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338343596&toolid=10001&customid=eb%3Ag%3Avms%3Aeb%3Ap%3A364208264027%3BCj0KCQjw3a2iBhCFARIsAD4jQB3WQFG66YX-OBGxdACK4sSqAP8qHwb-cskAqX9hIt9EwI_dPetQrQkaAmRqEALw_wcB&gclid=Cj0KCQjw3a2iBhCFARIsAD4jQB3WQFG66YX-OBGxdACK4sSqAP8qHwb-cskAqX9hIt9EwI_dPetQrQkaAmRqEALw_wcB

[545863]

Thank you, they both look the same. I'll check the wiring on mine tomorrow to see if that is the same. I don't know the part number, I did look on CMSNL to try to find it a while back and saw that they don't list the CB100N.

[Oddjob]

It looks like the Cb100N got black switchgear and the 125N got silver. Wiring looks to be the same, silver one is new and around £80, the Ebay one isn't but it's a lot cheaper at around £30. You could always get it ceramic coated satin black so it looks like new, do the other at the same time and refresh the handlebar look.

[545863]

My switch has a six wire block connector, not four wires?

[Oddjob]

Post a pi of the switch and the block connector.