16-volt CB125RS

Discussion in 'Classic Motorbikes' started by The Older Gentleman, Dec 7, 2008.

  1. That'll be why it's blowing bulbs, then. Bugger.

    There's a sort of plastic box, a bit like an elongated matchbox, with
    three wires coming out of it, under the tank on the right, and it's
    cracked, badly. The that must be the rectifier. The regulator, finned,
    is behind the l/h side panel. Or is it the other way round? Rectifier

    Anyway, revving hard gets 16v across the battery terminals....
    The Older Gentleman, Dec 7, 2008
    1. Advertisements

  2. The Older Gentleman

    Timo Geusch Guest

    Hmm. I'd go for regulator finned, given that the rectifier is just a
    bunch of diodes...
    That's be the regulator fucked then.

    Surprise, it's a Honda.
    Timo Geusch, Dec 7, 2008
    1. Advertisements

  3. Hmmmm.... wonder if a 400 Four one would work...?
    The Older Gentleman, Dec 7, 2008
  4. The Older Gentleman

    Simon Muir Guest

    [makes the Sign, etc.] you might want to try one from a CG125, or at
    least do a comparison. I've given away my Haynes for them, but at a
    guess the alternator is single phase and <10A, as the battery is small.

    Ought to be much cheaper, OTOH if you've already got one for a 400 Four,
    then 13.5V is the same everywhere...
    Simon Muir, Dec 7, 2008
  5. If I can get CB72 rectifiers/regulators for 20 quid off ebay I'm sure
    you won't struggle.

    Probably not the right one but item number 350134770474 is an example.
    mike. buckley, Dec 7, 2008
  6. Oh, Silver's has pattern items for many Hondas. I'll try them first.

    Remind me: the rectifier converts AC into DC an the regulator steps it
    down to 13.5-odd volts, right? Or is it the other way around?
    The Older Gentleman, Dec 8, 2008
  7. The Older Gentleman

    Krusty Guest

    Yep. The rectifier lets the magic smoke in one way & stops it doing a
    U-turn, & the regulator turns the magic smoke into a special type of
    heat that can detect if you own a Honda, & empty your wallet if you do.

    Off-Road Classifieds

    '02 MV Senna '03 Tiger 955i '96 Tiger '79 Fantic Hiro 250
    Krusty, Dec 8, 2008
  8. The Older Gentleman

    Pete Fisher Guest

    Useless the Japs. The Ities can make one little box that fails to do
    both for long.

    | Pete Fisher at Home: |
    | Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
    | Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
    Pete Fisher, Dec 8, 2008
  9. The Older Gentleman

    Ace Guest

    I fucking _told_ you it was the reg/rec. Would you listen? Would you
    Ace, Dec 8, 2008
  10. The Older Gentleman

    TOG@Toil Guest

    <Hangs head in shame>

    Never had one go on a small Honda before. But then all other 125
    Hondas I've had have been 6v....
    TOG@Toil, Dec 8, 2008
  11. makes for a nice bright light, though, for a while.

    I ran a CB100N at 8V nominal for a while, using a 6V36W headlamp (plus rear
    lamp etc.) allowed it to make lots of light from the nominal 76W alternator.

    fit a higher-wattage headlamp, it'll use the spare power and hold the
    voltage down :)
    Austin Shackles, Dec 8, 2008
  12. Correct.

    On a proper system, the regulator adjusts the alternator output to match
    demand... :)

    The regulator on hondas et al are finned 'cos they waste excess power to
    Austin Shackles, Dec 8, 2008
  13. The Older Gentleman

    TOG@Toil Guest

    Yeah, about 15 seconds.
    Funny you should say that - I've got a 35/35W halogen bulb that'll
    fit. Stock is 35/25W and main beam seems quite happy - it blows on

    Dave Silver quotes over £70+VAT for a new reg, and no pattern
    available. Electrex don't do one specifically for the RS, but reckon
    that one of their combined reg/rec units will work, for about £30.

    Hmmmmm..... this bike is starting to eat money....

    I ran it around at the weekend on the replacement carb, and it as
    great. So I stuffed the replacement carb's jets, float, etc into the
    carb that I'd taken off it (which is rather gunged) and it wasn't so
    good. So I put the jets back and now it's misfiring on *both* carbs.
    TOG@Toil, Dec 8, 2008
  14. The Older Gentleman

    Rusty_Hinge Guest

    The message <1irmblu.dz3swg1nsf3hgN%>
    from (The Older Gentleman) contains these
    Rusty_Hinge, Dec 8, 2008
  15. The Older Gentleman

    Rusty_Hinge Guest

    Mr. Miller had all that under control too.
    Rusty_Hinge, Dec 8, 2008
  16. The Older Gentleman

    Ace Guest

    S'wot I was going to say. I guess there may be some capacity
    limitations on smaller ones, but given that the target's a weedy
    little 125 it's unlikely to be an issue.
    Ace, Dec 8, 2008
  17. The Older Gentleman

    Hog Guest

    I had a similar problem once and fitted a 55/60 halogen bulb. It was dim
    at tickover, nice and bright at cruising revs, never burnt the filament.
    The Reg never got replaced.
    Hog, Dec 8, 2008
  18. The Older Gentleman

    crn Guest

    Yebbut please bear in mind that if the rectifrier is faulty and allows
    AC to get through to the regulator this will almost certainly destroy
    the regulator.
    crn, Dec 8, 2008
  19. The Older Gentleman

    TOG@Toil Guest

    Well, I've ordered a unit from Electrex. Slightly pricier at £550, but
    it does three things in one. Reg, rec *and* regulation of the AC
    direct lighting current for the headlight (as apparently that's on a
    different circuit).Sounds suitably trick.
    TOG@Toil, Dec 8, 2008
  20. The Older Gentleman

    Hog Guest

    Whew that really is becoming a money pit....
    Hog, Dec 8, 2008
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.