C15 Overcharging - I think?

[rhyatt]

If its a 2wire stator then it highly likely already 12v , hence your high idle charging voltage.
There are plenty of decent 4 wire reg rec available  to match.
Maybe look at your ht coil to see if it has any markings indicating 6 or 12v
Finally , I can't remember what battery you said you had as any conversion to 12v will dictate a new battery potentially
And bulbs of course , led?

[Derek996]

It sounds like the previous owner has tried to use 6V regulator from a Japanese bike. Many of these use a sensing wire from the switched side of the igntion, this is used to help regulate the voltage. Without it the output is usually too high.
The better solution, as suggested by the others, is to use a modern regulator/rectifier, upgrading to 12V at the same time.
The attached drawing shows the basic circuit for a 3 wire alternator with +ve earth. For the 2 wire alternator simply connect the 2 alternator wires to the 2 yellow input wires of the regulator and the regulator's output wires directly to their corresponding battery terminals.
You can ignore all the wires used to regulate the charge that go to the lighting switch, leaving them disconnected.

[Stevieo]

Thanks for all the advice,
Im confused that there can be 6 and 12v stators when they output AV volts though?

So is it the stator that is creating the overcharge then, due to the fact that everything else is 6v ? I have checked and bulbs are 6v too, there are no markings on the reg/rec or but the coil is definately 6v lucas.
So how much do i need to replace to make this 12v, is it the reg / rec, coil, battery and bulbs ?
Thanks again for all your help
Steve

[rhyatt]

2 wire stator are 12v .
If everything else is marked 6v , then cost out a replacement 6v stator , from one of the reliable suppliers .
( when I bought my 12v , 2 wire stator to convert my C15 to 12v it was about £90).
12v Ht coils are around d 20 to 25
A 12v reg rec is roughly 30 to 50
Bulbs , well 5 each give or take.
A 6v hooter will work on 12v , just screams a bit
It may be cheaper to convert to 12v.
Finally , get your multimeter on AC volts , disconnect the 2 wires from it to the bike , start it up and check the AC output whilst running, idling , no more than a fast idle will give you 30 or 40 v AC

See what you've got , before spending cash 

[limeyrob]

The big advantage of going 12V - to get a decent headlight, is less now that there are very good 6V LED bulbs.  If yu can get the 6V working as it should then with LED bulbs there's no rush to go to 12V.

[Stevieo]

OK, just started it up and have 35vac on the stator wires - so does this indicate a good stator - just dont see why this can be defined as either 6 or 12v if they both output 30-40vac then surely any one can be used and its the reg/rec that is perhaps wrong. I dont think im understanding all this correctly :-)
Steve

[V500]

They are 6V or 12V depending on the spec of the stator winding. Obviously either/both will output over 12V in use, hence the regulator.
IMO trying to revert to a 6V system would be a bit of a retrograde step; 12V batteries and bulbs are more readily available.

[Stevieo]

I dont particularly want to change the stator, it seems new and is outputting the correct voltage according rhyatt post above.

so at the moment heres what i know -

stator is 12v and good (i have no guarantee its 12v but a previous post sugests that 2 wire is 12v)

Reg / rec is unknown, 5 wires which is odd

Battery, bulbs and coil are all definatly 6v

so is switching to 12v as simple as replacing battery bulbs and coil?

[limeyrob]

Pretty much yes, I've got one bike on 6v and swapped the other to 12v. Its really depends on what components you have to hand.  12v coils and bulb are easier to get hold of.  Get an ID on that regulator, it can probably be wired for 6v or 12v.  Get that right and the rest is easy.

[rhyatt]

To be honest, going to 12v is a sensible  move.

I had an extra thought re the potential  conversion, what ignition do you have ? Cb points , condenser etc ? If so, then these will work fine with a new 12v coil.

It is frankly , a simple job, contact someone  like AO services for a 12 v reg rec, he sells decent stuff and is helpful if needed.
Take the opportunity  to make a nice mounting plate for the reg rec under the seat on the frame.
As mentioned by someone  else, join the 2 stator wires to the 2 yellow  RR wires and then arrange a fuse in the battery connection and a decent earth connection.

Change the ht coil , and ensure the polarity is correct (- on coil to the points if you choose to go negative  earth)

Change the battery of course

Change all bulbs , decide upon led if you wish.
Kick start and check charging voltage around 14v

[V500]

Anyone and anything but the AO Services item!
I suggest the DVR2 unit, which is far better and more reliable.

[rhyatt]

I may be wrong , but isn't the DVR2 for dynamos , not alternators?

There are a multitude of reg rec on the market , 4 wires , 2 x yellow 1 x red and 1 x black .
Ranging from 10 or 12 quid to 60 quid at Rex's speed shop.
Wassell unit in the middle for 35 and loads of cheaper ones on ebay.
Plenty from which to choose

[V500]

You're right!
I think when I see "AO Services" it triggers bad memories.
Never had an reg/rect from him and they may be good, but I wouldn't buy it on principle.

[Derek996]

Pretty much yes, I've got one bike on 6v and swapped the other to 12v. Its really depends on what components you have to hand.  12v coils and bulb are easier to get hold of.  Get an ID on that regulator, it can probably be wired for 6v or 12v.  Get that right and the rest is easy.

I think he'd be better chucking that regulator in the bin and replacing it with one which has known parameters and connections.

[Derek996]

OK, just started it up and have 35vac on the stator wires - so does this indicate a good stator - just dont see why this can be defined as either 6 or 12v if they both output 30-40vac then surely any one can be used and its the reg/rec that is perhaps wrong. I dont think im understanding all this correctly :-)
Steve

It is the regulator that sets the voltage, not the alternator. The regulator achieves this by burning off the unwanted energy as heat. So it is essential that the regulator is mounted where it will get cool air  and preferably attached to something that will act as a heat sink.