Electrical Problem

Evening everyone.

Having a bit of electrical problem with my ST70 after restoring it.

I installed a new Yuasa battery, after charging the reading on my multimeter was 6.5v. Fitted it to the bike and straight away I had the neutral light on (when ignition in on position) and a functional brake light without engine running. Sadly it appears the horn may not work as there was nothing when pressing the switch. So after a few days using the bike I noticed the neutral light was no longer coming on with the ignition switch. When testing the battery I was only getting 4.5v. I have also noticed that when turning on the headlight the light takes ages to come on and when it does it is very dull, the bulb just appears to 'glow' even when the revs are high. Before the restoration the headlight was good enough to see in the dark during high revs but not now. The other thing I have notice is when the lights are on the rear light appears bright but there is not brake light when braking.

I have tried using my multimeter to check continuity from the negative side of the battery connector block to every part of the bike that is exposed, ie, headlight connections, tail light, forks, coil etc and there is good continuity.

Any ideas why im suffering these issue with the headlight and why the battery appear to not be charging?

Rectifier!
Pete.

Uh-oh!

Any way to test the rectifier?

HI, yes there is. You will need a multimeter set to continuity. The rectifier has two connections. Since a rectifier passes current only one way. Place one lead on one connection, the second on the other. Swap the leads around. You should get continuity tone one way but not the other. This proves that current is flowing one way only. You may get a reading if the rectifier is the genuine Honda kit. Either way, that's what you have to do. Check that you have a good earth, and give the loom a once over for wrong connections or chaffing. Hope this is of some help
Pete.

With the engine running you should be getting a minimum of 6.8 Volts after the rectifier (red wire).
If you have a meter with AC (AC before the rectifier, DC after) capability (you can get cheapo analogue meters for £3 on market stalls), you should see about 8>9 Volts ac before the rectifier (White wire).
If nothing is showing and the rectifier has tested ok for one way continuity, I'd suspect a plug connection or the Ignition & Light switch contacts, before checking the charging coil. IE if you have AC Volts (Pink wire) from the plug next to the engine its not the coil.

Update:

So I have finally got round to trying your suggestions.

I bought a new rectifier and the battery now appear to be charging. However I am still having issue with the headlight. Could an issue with the on/off switch cause a problem like this and is there anyway I could test it? The reason I say this is the switch doesn't appear to 'click' when operated, just a smooth slide into place.