My Alpina Model 188  was originaly fitted with a battery. I do not have a wiring diagram but I assume that it will need to have a rectifier fitted. This was missing when I bought the bike. Rather than trying to track down an original rectifier that will probabaly be old stock, expensive and not work anyway I was planning of fitting a simple bridge rectifier from RS or other supplier of choice. Has anybody had an experiance of a similar mod and can give advice? I think most owners will not have expriance of Bultaco's with batteries so am not expecting a reply but thought I would ask anyway.

To be honest the bike will very rarely used in the dark so if the charging system does not work I will not be to worried as the battery will last a long time powering just the brake light.

I have a Frontera that has the resistor/brake light set up with no battery and this bike goes through rear light bulbs at an alarming rate so with this experiance I would not consider ditching the battery and going this alternative route. In fact I am planning to fit a small battery to the Frontera.

Stuart

Edited October 3, 20178 yr by twinnshock

Have a look for a Podtronics brand rectifier , 120 watt. So ac in , yellow and green -dc out to a battery, from there all wiring can be dc to headlight, tail / stop light. All this wiring and light assemblies has to be "above earth" that is no metal fixing onto frame or guards. The reason is the frame  is "live ac" and you can't introduce "dc negative " to the frame as well.

Now thinking cap on -- the horn will be ac and operates from power off the yellow wire to the horn then earthed out via button on the bars which are earthed to magneto green wire. Kill button is ac also, connect black wire off coil through kill button to the bars. When pushed it earths the ignition to the frame and engine shuts down.

Let us know how you go.