400F1 headlamp

[Bodd]

May be a daft question but does the engine have to be running for the main beam to work ? I have been doing some wiring today and have everything working apart from the main beam, the side/parking light works in both positions and when the key is turned all the way to the right and is removed, the pass light on the horn button is working (horn isn't yet), clock lights are working but the main beam isn't and neither is high beam, thought I would ask before opening up the lamp shell.

[Bryanj]

You have several positions on the key, main lights should only come on when key is in ignition position

[Dan]

Hi,
My headlamp works with the engine not running, but ignition on.

I also had non working horn. The connections just needed cleaning up in the left hand switch gear which is easier said than done - trying to hold everything in place including tiny spring when putting back together.
Dan

[Bodd]

Thanks guys, it looks like it's time to open up the shell, the horn is a new universal chrome one so I will try the old one before opening the switch gear as everything else is working.

[Dan]

I bought a cheap multimeter after I bought my bike. Invaluable for tracing opposite ends of wiring and checking for voltage at connections for things like horn, lights, etc 💡

[Bodd]

I have a multi-meter and a couple of long test wires with crocodile clips on each end that I made which usually solve most wiring problems, I just needed to know that it is supposed to light up on ignition without the engine running before opening anything up, thanks again.

[Bodd]

The horn was a quick fix it was just a bad earth on the frame, must have been all the layers of paint I used, I still haven't got the headlamp working on main beam, I haven't got a new battery for it yet and the old one wasn't the best when I got the bike last year, it is now completely flat so I have been using an old one off my R1 and now that is flat too, I have been testing the wires with my multi-meter and I am getting a circuit at the bulb when I turn the switch on and the bulb is fine.

[Lobo]

Hopefully its as simple as a dead battery.... but remember..

Multimeters are great tools... but they don't necessarily tell the full story. Electrical continuity, as measured by your meter, is simply passing a minute current through the circuit to confirm an electrical connection... but whether loom / connectors etc can actually conduct (say) 5 Amps is another story.  (most multimeters are powered by an AAA cell or two...  verifying indeed that they deal in small currents)

To clarify, imagine your starter motor had been connected with 2mm wiring. Using your meter all would check out ok... but in reality there'd be no hope of the starter working due those wires being insufficient to carry the required 120+ Amp load.

WAY too wordy Bodd, apologies... but hope it clarifies that sometimes meter checks on old looms can be misleading... you really do need to be sure all that wires, connectors, earths, switches etc are clean / upto spec.

Not denying tho'... wouldn't be without my 'meter.... it's a fantastic bit of kit.

Simon

[Bodd]

Thanks Simon, not too wordy I'm grateful for all advice offered, electrics are the worst thing for me when restoring bikes. I charged up the old R1 battery and had another go, what I found was if I connected one end of my wire with the crocodile clips on it to the wire in the loom connection junction (in the big rubber shroud under the tank) and the other end to the blue headlamp wire in the shell the main beam works so it looks like the blue wire needs replacing, thanks for pointing me in the right direction.

[Lobo]

Hi again,

Yup, jumper leads are often the way to go..

'Weak' spot in all this may simply the handlebar light switches... & sods to get out & service, A starter for 10 could simply be to copiously spray switch cleaner into the guts of both the main switch & full / dip beam switches; exercise them a good few times... and hope. (switch cleaner spray from Maplins / Halfords)

If you substitute the main 50W/35W bulb with say, a speedo illumination bulb (2W) ... and it then works... it really does suggest dirty / corroded connections / switches / wiring somewhere. (put the small bulb between the headlamp bowl blue & earth.... and then white & earth)

Otherwise the headlamp bowl is a rats nest of bullet connectors all trying their damnest to detach from one another... but you knew that...

Good luck.

[Bodd]

I know all about the tricky switch gear and all the wires in the headlamp shell, I totally stripped the bike, mind you compared to the RD I restored the headlamp on the 400/4  is like Old Mother Hubbard's cupboard. Anyhow I managed to get the headlamp working, it was the blue wire, I didn't think it was the connectors because I had changed a lot of them when I refurbished the loom and added a fusebox which a previous owner had bypassed.

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[Lobo]

Great.. sorted, and all looking shiny & new.

[Bodd]

Thanks for the help, I will be able to sleep tonight   

[Dan]

Glad you got that sorted.
A lot of my time was spent sorting the electrical system on my bike - connectors were not corroded but just dirty and had high resistance and so were getting hot, enough so that you could smell burning. I used contact cleaner and crocus paper on the worst areas.

[Lobo]

Hi Bodd,

SO impressed by your RD250 'Window dressing'... want one too, but to date, the most I've been allowed get away with is a nice framed print of my bikes in the living room..

Anyways, just read your '400 Cafe racer blog... fantastic. Pi**ed off though 'coz I've recently sent hubs off for polishing.. your blog has inspired me to get busy and rather have a go myself. (in future)

Cheers,
Simon.

PS... lived 6 yrs in Lytham St Anne's, & another 6 in Chorley.... where I think it rained everyday.. Where abouts in Lancs are you?