1980 xs650 chopper running batteryless with a PMA

[Mjohnm]

Anyone else happen to run this? I have the Boyer Bransden ignition and 3 phase powerbox battery eliminator, and Mikes XS PMA. Mostly looking for ideas on where to mount everything if anyone had pictures of their bikes, and also figuring out how it’s all connected.

The biggest complication from what I understand is not being able to use the original ignition system if I wanted to run batteryless, and that’s where the Boyer Bransden ignition comes in, along with the 3 phase powerbox. I haven’t really seen anyone do this specifically and I know people have previously said it’s not ideal getting rid of the TCI but here we are, still aiming to run without a battery. Anyway any insight and pics of your setups would be helpful. Cheers!

 

[Signal]

I have no experience with the powerbox, but some with Boyer Bransden Ignitions.
Boyers do not like under voltage they can over advance. Kick starting may be problematic with low rpm (from the kick ) generating low voltage such that that the ignition will not operate correctly .
Have you spoken to Boyer Bransden about your particular scenario nothing like getting it straight from the horses mouth.

 

[Its been a long time]

I agree with Signal. Speak to Boyer Bransden. I'd use a battery, it doesn't need to be a large one if there's no electric start.

 

[Mjohnm]

Ok the instructions from Boyer Bransden were as follows

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The 3-Phase PMA (alternator) output wires should be connected to the three yellow wires of PBOX00105, in any order.
PBOX00105 Red and Black 12 volt wires connect to battery + POS (after its fuse), and the Neg frame earth, respectively.

UK XS650's should have 2 RED/WHITE wires coming from the ignition and kill switches, these connect to the red wire of the Micro-Power ignition unit and +terminal of its ignition coil.

The white wire of the ignition unit connects to frame earth and its 2 bi-colour wires (BLK/WH and BLK/YEL) connect to the same coloured wires of the stator plate.

-----

I asked how this system could run batteryless, and they replied -

From Boyer bransden - "Yes. You can use the PBOX00105 sheet...

The 12 volt battery shown in the Neg earth wire drawing should be omitted, the Power box RED wire connected to the 'battery side' supply of the XS650's ignition switch.

Engine starting is going to require more effort without a battery. "
------

Now I'm wondering whether I should include a smaller battery somehow because having this thing hard to kick over is exactly what I wanted to avoid.

 

[MrBultaco]

650 Central used to sell an 12V 0.8ah battery for builds using Boyer ign. Approx.5" X 3" X 1.2"

 

[Mjohnm]

650 Central used to sell an 12V 0.8ah battery for builds using Boyer ign. Approx.5" X 3" X 1.2"
View attachment 375018

Thank you for this. So I would think this could just be substituted in where the original battery is in the schematic.
Does seem odd that I'm converting to a battery eliminator to run with a battery but as long as this works. Haha.

 

[Its been a long time]

Seems to me that the battery eliminator (a capacitor?) is redundant when you fit a small battery.

 

[MrBultaco]

^^^^
I agree, just offering another suggestion. What Boyer said below :

Engine starting is going to require more effort without a battery

Which means to me that more and more kicking is needed...