Flippin' 6v electrics!

[KirriePete]

Guinevere the GN400 has started blowing headlights, bad girl!  Initial suspect was the rectum-frier, but that checks out OK (it is a simple diode after all!), then checked the volts at the headlight - between 5 and 9 depending on revs, spot on!

Then I found that the rear light fitting had rusted into oblivion - all the wiring crumbled to dust at the first touch.  Rummaged around and came up with a rear light unit from a Yam SR125 which I managed to bodge skillfully engineer into place, all seemed well.

The lad started up the road tonight and got about ½ a mile before, you guessed it!  Any suggestions as to what to look for would be welcome.  The wiring is a bit of a mess with multiple previous owners having had a crack at working around various corrosion spots, so there's lots of bullets, spades and soldered twist-wraps around with a variety of wires mostly in domestic circuit brown, blue and green/yellow - in short, any colour descriptions would be wasted!

Anyone?

[Jez F]

I've got a workshop manual lurking in the shed, I'll dig it out tomorrow and have a look at the spaghetti diagram, should be able to sort something out. I did have one for a DR750 blown up to A3, makes it a lot easier to read.
 Jez

[Jez F]

I eventually found the manual, nowhere near where it was supposed to be, but I did find loads of other stuff that I had forgotten about. It turns out to be for the SP400, but there isn't a lot of difference as far as I know. I can get the wiring digram for uk spec bikes blown up to A3 and post it to you if you want.
Jez 

[KirriePete]

Thanks for the offer Jez, but I've found the workshop manual with a wonderfully clear extract of the lighting/charging circuit with all the checks.

Current ('scuse the pun) thoughts are the battery is a bit below par and isn't regulating the output as well as it should.  Goffy does a 6v AC Regulator that should work around the problem - fingers crossed (well, not when I'm wiring it in, obviously.  I'd get solder everywhere!).  I know a battery is cheaper, but I like the idea of having definite regulation as against "the battery kinda does that, if it's fit", it's neater and appeals to a certain element of my (tiny) mind!

Will post up results as and when.

[johnr]

in my past ive had an sp400 and a gn400, both had 6v electrics and both at various times suffered recurrent blowing bulbs both front(genny powered) and rear (battery powered) assuming that the rectifier isnt duff, then the finger of suspicion always ended up with duff earths, check the battery earth, cheack and clean the light earths, in fact, as its just 6v, check all the earths, clean them and coppaslip them or acf50 them, any slight bit of corrosion in them will cause enough resistance for the lighting to go belly up and start blowing bulbs.vibration wont help either. ive seen led tail light boards, made by paul goff iirc that will solve this too if its got any connection with excess vibration.

and my gn engined off roader went like the absolute clappers when i fitted a carb from a klr650!!

[guest146]

I would have said 9v on a 6v system is too much On a 12v system you only need 14v to charge fully so 7 and a bit volts would be enough.

ken