Forum

[MrGinger]

Hi Chaps.

I have finally managed to get my 1953 Model G back on the road and took her out for her maiden voyage today. She's still very much an oily rag but runs really well. I managed to get 60mph out of her which I was quite surprised by, this is my first classic bike and I though that it would be slower. Not everything is working as should be yet though…

The electrics were converted to a 12v system by a previous owner and I now have everything working except for the charging circuit. I have tested the generator and that all appears to be fine but as soon as I connect up the existing Control Box then the system shorts and blows the fuse that I fitted on the battery earth cable.

The existing Control Box has obviously been modified as taking off the cover shows a modern sealed circuit board with cooling fins that has very badly soldered wires attached. Looking at the Hitchcocks part listing the correct part seems to be LU/37097A but I am guessing that this would be for a 6v system.

Does anyone have any experience with converting to a 12v system or have any idea what part I need to buy?

Thanks.

[Revband]

Your first check has to be to ensure it is wired correctly, these bikes were positive earth, they can be changed to neg but it is a bit complicated and requires the dynamo to be changed internally, if you are unsure how to wire and test a dynamo system then you would be well advised to find someone locally who does to take a look. Or carefully examine the circuit diagram.

[Revband]

Just to clarify, the internal changes to the dynamo are only needed when using an electronic regulator,

[MrGinger]

Thanks Revband. The wiring diagram in the service manual show the bike to be a negative earth system and this matches with how the bike was wired when I bought it. Are you aware of anywhere that might sell the right kind of regulator? I have contacted Hitchcocks directly but haven't has any response back yet.

[Revband]

There are plenty of suppliers and makes availability. A good one is from, aoservices.co.uk

[MrGinger]

Thanks again Revband, that link was really helpful, the regulator fitted to the bike is from AO Services. So it turns out that the whole charging system is in a bit of a mess... The wiring and battery on the bike were set-up for a 12v negative earth system whereas the regulator was fitted and set-up for a 6v positive earth system. I tested the dynamo on the bench last week using an electric drill and it was supplying a steady 10v but when fitted to the bike the supply is very erratic and jumps up to 18v. When I put a load on the output (i/e a bulb) then the supply completely dies. I'm pretty sure that the dynamo needs reconditioning so I'll be pretty much sorting the system out from scratch. Does anyone have any advice about the best set-up? Should I be dropping back to the original 6v or go for 12v? Do I even need to bother with a battery?