Model 31 Charging

John Walls · Post by **John Walls** » Fri Jul 08, 2011 12:06 pm

Hi
I am having trouble with the charging on my recently renovated 31.
I am not sure if it is a problem with the dynamo or the regulator.
I recently read an article on how to check the dyno by bypassing the regulator and connecting straight to the ammeter but I can't remember if it was in the owners club magazines technical section or Classic Bike's section on "How to". I have gone back through recent copies of both to no avail.
Can anyone please advise on how to check the dyno by bypassing the regulator and how to check the regulator or where I may have read the article.
I have a new battery.

Rgds
John

Groily · Post by **Groily** » Fri Jul 08, 2011 12:47 pm

Start with the dynamo John.
Basic test of its function as follows: Disconnect the D and F leads at the end cover. Link D and F sockets on the dynamo with a short bit of wire shoved up them (or whatever). Start engine and maintain it at a fast idle. Connect this loop of wire to a bulb such as a headlamp one, and earth the body of the bulb to the bike. The bulb should light and get brighter with more revs. It should go dim/out at very low rpm. Don't rev it up much -too many revs and it'll pop for lack of regulation. You could use a meter on dc volts scale, but bulbs are good because they prove delivery of real watts to sustain loads, rather than just a voltage reading.

If that works fine but no charge down the line, then you'll need to look at the regulator and cut-out (or the basic wiring for continuity etc). Often the cut-out is the basic culprit as in it won't cut in. Suggest have a read of the Lucas service sheets (see Christian's archives or search the forum) before playing with it, if that's where the problem ends up being. Lots of people love mechanical regulators because they can be played with, but I have to confess to not being of their number as I always go solid state. Some of these learned folk (they'll be along soon enough!) are better sources of help on setting regulators up if that's what you're going to have to do. I've given all mine away or junked them, so haven't played with one seriously this past 20 years.

en7jos · Post by **en7jos** » Sat Jul 09, 2011 2:09 am

A guide with pictures is here:
http://www.matchlessclueless.com/how-to ... as-dynamo/
Not sure about how you'd use the bikes ammeter to test the dynamo, but all the required messing about with the wiring is surely more hassle than using a bulb and/or multimeter isn't it?

Some of the old school diehards will no doubt be along shortly though to offer more useful words of wisdom on mechanical regs...

But my vote is also with a modern solid state regulator if your's is found to be playing up. I've got the DVR2 (see here) which I've found excellent so far and which allows a simple conversion from 6 to 12v.

Hope this helps... James

John Walls · Post by **John Walls** » Mon Jul 11, 2011 10:47 am

Gents
Thanks for the info, just to clarify. The D and F terminals are joined with a piece of wire then another piece of wire is connected from either of the terminals to the contact on the bulb with the bulb then being earthed to the frame. Is that correct.
Rgds
john

SPRIDDLER · Post by **SPRIDDLER** » Mon Jul 11, 2011 11:40 am

Yes, that's correct John.
I use a piece of twin domestic mains flex (cut a foot or so off a table lamp lead when SWMBO isn't around), keep the two wires at one end of the flex separate and jam one of them into the 'D' socket in the dynano and the other into to the 'F' socket.
Twist together the two wires at the other end of the twin flex and connect (solder if poss)this to one of a headlamp bulb's soldered base pip. Run th'engine and place the metal cap of the headlamp bulb against an earth (clean bolt, frame part etc) when the bulb should brighten as revs increase.
Instead of holding the metal cap of the bulb against the earth it's easier if you can rig up a croc clip or similar (or solder the wire to the metal cap) then both hands are free to twiddle the throttle, scratch head, drink tea etc.
If you have a spare headlamp bulb holder this saves a lot of soldering.
Don't leave the soldering iron on the headlamp base pip too long or you could damage the bulb's internal connections.Edited by - SPRIDDLER on 11 Jul 2011 11:01:47 AM

John Walls · Post by **John Walls** » Mon Jul 11, 2011 1:18 pm

Brilliant, thanks very much Spriddler.

wilko · Post by **wilko** » Mon Jul 11, 2011 10:35 pm

Report back immediately!

John Walls · Post by **John Walls** » Sat Jul 16, 2011 3:12 pm

Worked perfectly, thanks.