William W

XS400 New Member
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Meridian, ID
Hey XS’ers. I’ve read a few threads on some similar issues from others, but I’m not quite finding the answers I need.

I’ve got a 1979 XS400f that I am turning into a brat style. I’ve done a lot of upgrades, including the motogadget M unit blue, motogadget gauges, and a solid state regulator/rectifier.

I’ve attached a PDF here from Revival Cycles, showing the wiring diagram for the Type A charging system.
…the three white wires coming from the ac generator are connected to the three white wires from the reg/rec.
…I have the black and white wires connected to the green and black wires which I believe are coming from the field coils of the bike.
…the red/white wire of the reg/rec is connected to the battery via a fuse.
…the green wire of the reg/rec is grounded.
…the black wire of the reg/rec is going to the output of my m unit.

Problem 1: the charging system does not appear to be working with this configuration. The bike is running.

Problem 2: I can’t get either the neutral light or oil pressure light to work. I’ve replaced both the neutral switch and the oil pressure sending unit. I have these directly connected to the input of the motogadget indicator lights.

Help appreciated.


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The fact that on their website Revival lists all years of xs400s as Type A charging systems makes me wonder about them, since Yamaha changed types around 79/80.

Changing the bike from A to B, or vice versa, isn't too difficult. Just need to switch whether the black wire in the regulator connector goes to ground or brown/+12V.