I am trying to get my bonce around the electrical system, I have seen a bunch of modern rectifiers to replace the old mechanical ones.
I see the classic bike modern replacements are like 40 quid.
Would one be able to use a regulator off a japanese bike? theyre cheap as chips second hand or new. Like the one I got for the honda c70 I have.

Hi Maxwell..No, you couldn't use a Jap rectifier/regulator...Their job is to convert AC current from the alternator to DC for the system and to regulate the alternator output..a completely different system to the BSA one, which uses a dynamo that already produces DC voltage and consequently an entirely different method of regulation...Ian

email (option): ian@wright52.plus.com

aw
not good
I have another question, can I use my 6v honda battery?

Battery should work just fine....if small enough, put it inside a original hard rubber case and no one will notice.

If the Honda battery has a vent tube, arrange it in such a way as to prevent any acid or vapor from dripping onto the bike in case of overcharging; if you use an old casing, there should be enough space inside to allow the new battery to vent inside the case, capturing any acid...the old original batteries seemed prone to venting onto the chain cases.

The new gel cell batteries seem to work the best; a small unit will fit easily into an original style hard rubber case, and has no venting of fluid or vapor to deal with.

JDE

email (option): teladelujo@msn.com

Definitely consider forgetting wet batteries, the way forward are these:
http://www.dynamoregulatorconversions.com/cyclon-batteries.php

nice one that looks good

i just have a cheap japanese battery in my bike for 5 years last year i didnt disconnect it when i first started the bike it was flat ran the bike for 3 miles for the MOT and was able to test the lights and horn without the engine on

email (option): roger.beck@node6.com

Roger, I wouldn't throw away a traditional lead acid type battery if I bought a bike with one fitted, but if I've got to buy one I buy the cyclon type.
They fit in a dummy period battery box & I got mine cheap off www.Ebid.com for £8 each.
I recommend the Cyclon type because years ago I had a battery overcharge on a Triumph & somehow vent onto my freshly chromed exhaust taking off a patch of chrome.
I like not worrying about vent pipes coming adrift & I find these last many years, one I bought in 2004 lasted 6yrs.

Hi, i have a small gel batterie wich works very well for years now. I even put it on its side to fit the box. No trouble.
I heard gel batteries should always be charged, otherwise they will be damaged

I've just gone mad and bought a Shorai Lithium battery - i am running 12V system. 9AH fits in the black battery box with plenty of space to spare.
Not that it matters on these old bikes but i just about threw it back over my shoulder when getting it out of the box - they are incredibly light.
I havent found a source for Cyclon over here and a Motobatt lasted 5 minutes.