1978 XS750 Wiring Help please!


XS650 Enthusiast
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Nashville TN
Hey guys! I just bought a 1978 XS750 as a project bike. It was pretty stripped and the frame had been chopped for a cafe project. I got all the lights I'd need to get it back on the road, new aftermarket switches for the bars (the old ones were shot), and a bunch of other stuff. I'm having a heck of a time with this wiring. I can get the bike to turn over off the starter button but the kill switch has to be in the off position for some reason. The biggest problem I'm having is the turn signals. Can I delete the flasher canceling unit and the rear light unit? If not, is there any other way to simplify this whole thing? Last time I tried, I pulled in the clutch and brake levers at the same time and the neutral and oil pressure lights came on..... I'm not a wiring newby but holly crap!
I don't have a schematic on that one and don't know the wiring on the aftermarket switches - but I'll take a couple stabs at it.

The stock kill switch is in series on the ignition circuit hot wire (usually R/W on Yamaha) - sounds like yours is going to ground when on.

You should be able to unplug the cancel unit and the light checker as they should be in parallel.

The lever switch thing is curious; typically the meter lights have switched power on with the key and the neutral switch supplies ground in N and oil sender also supplies ground when no pressure.

It'll take a wiring diagram and pics or drawing of existing circuits and switches to resolve.
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Yeah I have the clymer manual for it. Everything says it's wired up right and it kinda works except the signals and the horn, but it seems like everything is tied into everything else. Is there any way to simplify it all , rip out all the flasher and rear tail light units and all that crap and just start from scratch?
Maybe try jumping an extra wire from battery negative to threaded signal base and then horn pink terminal and see if that helps that part. Sometimes the horn needs slapped (really) some with your hand while pressing button. Same treatment of signal flasher - I know it's abusive - but works.
Yes, mostly it will. You should have TCI ignition with pickups and igniter and a combined regulator/rectifier on the alternator. So, more similar to a 1980 or newer 650