Hello everyone, I'm trying to find out why my headlight and tail light have stopped working (but stop light and horn work okay.)
I've charged the battery and it is showing about 6.2v, so that's okay.
Tested the headlight bulb: okay.
So I guess the next step is to check power is reaching the switch. Here is my first stupid question of the day (please see photo attached): does the black plastic bit just pull off the metal bit to expose the connections? (I'm guessing so but don't want to pull too hard in case not!)
Thanks in advance.
Phil.
Here's the photo.
Yes just gently pull it off.
Photos show what you will see.
I suggest you also check the dip switch.
Thanks very much Julian. I'll let you know how i get on. Phil.
Her'e what I found when I pulled the switch apart (see photo). I guess the wires simply push in? Don't seem to want to pull out though?
Anyway, I set my multimeter on DC volts and connected one end to the battery and pushed the other end into connection 2 on the switch, which I believe is incoming to the switch from the battery via the ammeter. I expected to get either about 6v or 0. But I got about 4.5v. Why could that be? Something wrong at the ammeter?
Phil.
I've just lost and regained my connection to the website so this might come to you twice - sorry if it does. Anyway, I'm confused. Having measured 4.5v at the light switch, I checked the voltage at the ammeter. Where three wires leave the ammeter, I got 4.5v. Aha, I thought, if there are about 6v where the single wire enters the ammeter, then the problem is at the ammeter. But the reading was 0. How can that be? Phil.
I am far from an expert on wiring, but surely it's a process of elimination.
Looking at a wiring diagram of a B40, you've got one wire from the negative terminal of the battery that goes to the ammeter, it should be brown and white according to the diagram I found.
If you put one probe of the multi meter on the ammeter terminal where that wire connects and the other on to the positive terminal of the battery (if you can reach it) do you still get 6v. if you can't reach the battery any metal part of the bike should do. if the multi meater doesn't read 6v then there is a problem in that length of wire, if you've got 6volts then you know the wire is sound. Then try the other ammeter terminal to see if the problem is in the ammeter.
persistance pays off.
Our messages passed in the ether I think Bees! Phil.
Except mine doesn't seem to have reached the site
Again, two of these might arrive, as I'm having a bit of computer trouble. Here's an update in case anyone is still interested: walking the dog, I had a brainwave: maybe I connected my meter to the wrong terminal at the battery! So when I got home I put it on the +ve (earth) terminal and got readings which make a bit more sense: very little at the switch; less than half a volt where three wires leave the ammeter; 6v where the single wire enters the ammeter. So I guess the problem is either a duff ammeter or a duff connection there.
It does help if you connect the meter to the correct terminal! Not sure where the 4.5v came from when I wrongly connected.
Phil.
It seems logical to me that it's a problem with the ammeter as 6v has to find its way through the ammeter where it gets split into 3, one for the main bulb, the side light and ignition.
I've got to replace my ammeter on my bike later I'll see if I get the same reading on both sides of the ammeter and post back.
I've checked the connection and it appears sound, but no volts there. So I guess the ammeter is a gonner? Phil.
Looks like it is. Just checked mine and I get the same reading on either terminal.
I expect this will sort the non start problem too as the coil probably not getting 6v either.
Worth checking just to see. With the ignition on put the multimeter probes on the coil pos and neg.
Okay thanks Bees, I guess I'll order a new one (these old bikes are money pits, aren't they?!)
I suppose it's best to get the Lucas one if it fits. And I imagine there'll be an "O" ring or felt washer or something underneath the bezel.
Fingers crossed.
Phil.
There should be an o ring between ammeter and cowl. The old one from your carb will fit.
I just got one from feked. It was 21 quid incl vat and postage. There are cheaper ones but they dont look as good in my opinion.
I expect, but not sure yours is a 1 and 3/4 inch diameter and -8 -0 +8 reading.
They can seem like money pits. Hopefully these things are a one off cost and once sorted they are sorted for good. Once there all done keeping at a sorted level is much easier.
I suppose you have to expect it. Unless you know otherwise its sensible to assume that a 50+ year old bike is going to to have stuff to sort out. Its part of the charm! The feeling of satisfaction you get in solving these problems is worth it.
What make is it, Bees? Phil.
Search this part number on feked.com
fkamm002
But measure the diameter if yours. It'll probably br 1 and 3/4 inches. But some are different.
Thanks Bees.
By the way (see photo), regarding the light switch, do the wires just push into it? I tried to pull one out but it wasn't having it.
Phil.
The wires dont pull out of the connector.
Oh. Just as well I stopped pulling. How are they put in?
Never taken one apart but I think that the brass terminal to which the wire is attached has a latch which engages in the body. In service if they failed a replacement was available with bullet connectors, like the one in the photo.
If you want a quick check that the ammeter is indeed the problem just short the connections.
Or, disconnect the feed from one side and add it to the wires coming from the other.
If the problem is an open-circuit ammeter then everything will be fixed - except you'll get no reading on the ammeter of course!
If that doesn't change the behaviour then it suggests the problem is elsewhere.
Cheers,
Bernie
Morning all, You will of course be on the edge of your seats. Here is the next thrilling instalment. Berniej's suggestion for testing the ammeter (no doubt absolutely obvious to him, but to me a great revelation) was very useful. I put a little bit of wire across the two ammeter connections, watching the headlight out of the corner of my eye, and...the gloom was not lifted. So, I thought, maybe it's not the ammeter after all. Then, whilst fiddling around to make sure my bit of wire was making a reasonable contact, I noticed the rear light come on! Hallelujah! But why no headlight? I kept fiddling with the little bit of wire. Then the parking light came on. Then it didn't, even when the rear light was on. So I guess that's a bad connection somewhere for the parking light. But still no headlight. So I thought I'd check the headlight bulb again, and when I took off the bayonet-like fitting I saw the bulb was crooked in its hole, so maybe there wasn't a connection. Then, trying to straighten the bulb, I broke one the bulb contacts off (I have a feeling I've done that before) so I need a new bulb. Anyway, to sum up at this stage, it looks like: 1. the ammeter's had it; 2. there's a poor connection for the parking light; and 3. the headlight bulb needs to go in straight in future. I'll get an ammeter first, before I sort the bulb contacts, so I don't have to fiddle around holding a piece of wire on the ammeter contacts. Can't say it's not interesting. Okay, maybe you can. But I'm enjoying it. Phil.
Is your headlight properly earthed . It can be working ok whilst fitted but I find the earth wire is always iffy when its just hanging there . The side light , parking light , has its own earth .
I'll check. Thanks ducati2242.
Ordered an ammeter from Feked (thanks again Bees.) Looking at the brass bracket which holds mine in place (see photo), I must say it's a flimsy little affair (see photo.) You'd think there might be a little flange on each end of the bracket, wouldn't you? It's also very thin brass. Oh well.
Also ordered a headlight bulb from Draganfly.
Why am I telling you all this? (Note to self: Get life.)
Anyway, looking forward to getting my bits. Phil.
Phil.
Useful tip Bernie about the Ammeter. Cheers
I had a problem recently with my electrics.
The headlight was much dimmer than it used to be and after checking the battery I tested the voltage to the headlight and found it to be around 4-5 volts. I then went through the wiring loom, just cleaning and checking all the connections, and problem solved.
There must have just been an accumulation of corrossion along the various connections leading to a resistance high enough to cause the problem. 6 volt systems are particularly sensitive to this.
Cheers
Pete
If I'm rewiring I'll usually take a dedicated earth wire from the battery up into the headlamp and connect with a large ring tag to one of the headlamp fixing bolts. Then I run earth wires for the local bulbs back to that. It avoids poor earthing issues with dirty or loose connectors or other poor metal to metal contact. Might need earth tags fitting to e.g. headlamp shell or speedo.
Sometimes this just leaves the horn button operation reliant on the handlebars being well earthed (depending on type but many work like this). Running an earth wire to the bars can be awkward but might help with iffy horn operation.
Cheers,
Bernie
New ammeter fitted. Lights now all working okay. Very pleasing. Thanks again everyone.
As advised by Julian, I fitted the old O ring off my carb onto the new ammeter, under the bezel (even though there wasn't one there when I removed the old ammeter.) Do people also use any silicone sealant or anything like that, or is that not necessary if an O ring is fitted?
Phil.
The O Ring should protect it.