NC 31 Reg/Rec issue?

[Fladdem]

Hi, I've heard about Honda reg/rec issues on nineties bikes and I was wondering what the symptoms were?

I've tried googling and apart from the obvious flat battery and not charging, I can't find much on it.

Since early October, I've had an intermittent fault with the Super Four. While going along, the power will just drop off and I'll end up crawling to a halt, feels like someone knocks the kill switch. I'll get off and wait for a bit, then it'll bump after about 15 minutes and I'll get to ride it for about 5 minutes before it dies again. As if something is cooling down.

I genuinely believe it's the reg/rec as the battery doesn't seem to charge itself while riding, it happens more when it's a warm day, and it doesn't seem to cut out when I have a fully charged battery.

Basically, I just want confirmation

Thanks.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[Hong Kong Phooey]

Overcharging and frying the battery is one mode of failure.
Above 15v output (IIRC) means rectifier is questionable.

Undercharging <13.5v or no output is the another.

Rev it with the lights on, should see increase in brightness - but really you need to test DC volts at battery is between 13.5 - 15v at about 4.5k revs

Above is general guide for 12v motorcycle, not NC31 specific

[jaffa90]

Stick a voltmeter on the front,
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2060353.m570.l1311.R4.TR12.TRC2.A0.H0.Xvolt+meter.TRS0&_nkw=digital+voltmeter&_sacat=0

[Fladdem]

After weeks of messing around and not doing anything with the bike, it would appear, I had a duff rectifier to begin with, after testing. I then ordered up a new rectifier and got a new battery for it.

Messing about again today, it's still not charging at the battery.

I'm looking at about 33-34V at the alternator, at about 3,000RPM, there's a strong earth everywhere, the new reg/rec tests fine, as far as I can tell.

I then had a thought that the one on the Varadero 125 might be the same, I don't think it's identical, it doesn't quite fit in the gap, but when the earth is bolted up and it's plugged in, the battery is charging at about 14.5 volts, as expected.

Is it possible to get a duff rectifier? Could the 34V from the alternator be too much for the regulator and it's fried it again?

Without the battery connected, it wouldn't rev at all, so at tick-over, with the new reg/rec, not the Varadero reg/rec, the voltage at the battery cable terminals was only about 9 volts, would that point towards a brand new duffer?

Thanks

I need to work on my electrical knowledge more, I think it should be fairly easy in theory.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[smallfrowne]

if the varadaraderio one works then aye, looks like a duffer to me

Look out for a MOSFET R/R on ebay. I managed to get one for about £20. They don't run so hot so live longer in the daft places that Honda liked to put them (lack of cooling).

Rectifiers on a lot of bikes are made by shindengen, probably almost exclusively. There's a code printed on the side, if it says FH020, FH012, or SH775 it will be a mosfet, but this is obviously not a definitive list, I just can't remember the full details - but there is an arse load of info on google, probably too much. You only have to type FH020AA to bore yourself senseless.

MOSFET R/R's were fitted to later R1/6's, kawasaki ninja things, you know, newish sports bikes, so there's a few about, and a few with spade connectors (what I managed to get), not the fancy (but pricey) waterproof blocks. I fitted mine to the NC30.
____________________
'90 VFR750; '89 NC30; '95 DR650; '89 CD250U; ~'82 CG125; ~C90

[smallfrowne]

Orrrr the new R/R has different pin outs to the old one, just for fun, and the polarity is reversed or sumfink.

Edit: Wait a minute, I read some of your post wrong, so ignore that ^^^ .

What was the voltage at the battery with the new R/R, battery connected and revs ~3000rpm?
____________________
'90 VFR750; '89 NC30; '95 DR650; '89 CD250U; ~'82 CG125; ~C90

[Fladdem]

The original was an SH609-12

The new one I got has SH603-12 on it, but it all plugs in and has fins, unlike the original, which was definitely fried.

The Varadero R/R no longer works, at 3000 RPM, I'm getting 12.8V, which is battery voltage, I may have ruined that one now.

I am beginning to suspect something else at fault. As far as I'm aware, the charging system is basic, generator to R/R to battery, with no relays or anything in the middle? I am certain I have good earths, I've cleaned them all up, I don't have any wire breakages, good continuity everywhere, I'm confused and scared now.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[Meatybeaty]

Have you got a Workshop manual

[Robby]

You blew the original reg/rec. This happens.

You may have blown the Varadero one by shoving too much current through it. Shunt-type reg/rec (most of them) will take in a certain amount of AC power - usually 30-60 volts - and turn it into 12V DC. They aren't perfectly efficient, so some of the power gets turned into heat in the three shunt diodes. Over time this heat kills the diodes, which is why reg/rec start to die slowly, then all go at once.

The varadero one was designed to work for about 10 years on the output of a varadero alternator. You probably killed it in a day with the higher output of a super four alternator.

Get a MOSFET, they work. One my old VFR750 I used the FH020 reg/rec with the Triumph wiring harness, fitted to the Honda plugs from my old one to make it play nice with the wiring loom.

Do not buy a £10 reg/rec from China on ebay. It will take a month to arrive, then not work.

[Matt B]

Have you physically looked at the stator and checked resistances between the yellow wires?
____________________
stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.