SOHC vs DOHC regulator rectifiers

[Supercoyote]

I'm finding a lot more parts for DOHC combined RR's than for SOHC. If I bought a DOHC combined unit, could it be adapted easily to a SOHC bike? Or is there a critical difference between the two systems that can't be rectified with wiring changes?

 

[BBS360]

I'm finding a lot more parts for DOHC combined RR's than for SOHC. If I bought a DOHC combined unit, could it be adapted easily to a SOHC bike?

Yes. How easily depends on the year of SOHC bike.

Or is there a critical difference between the two systems that can't be rectified with wiring changes?

No.
The earliest XS400s (with mechanical regulators) grounded the field coil, later models connect it to +12V. The regulator function differs to match.
If you have a later model SOHC you may just have to redo the connectors to match.
There are previous threads that cover the subject and the wiring diagrams will show how your bike should be connected.

 

[Supercoyote]

The earliest. It's a '76 XS360 wiring harness and associated components with an 80 400 engine swapped in, still using points and condensers. I read through the rewiring guide but nothing is jumping out at me. If it involves more than just re-soldering existing conections to the new harness, a NOS R and R looks like the way to go for me

 

[BBS360]

The 360 harness connects the field coil to ground and the green wire from the stock regulator provides switched +12V.
The original '80s harness connects the field coil to +12V and the green wire provides switched ground.
The DOHC bikes are the same and their regulators switch ground.

The ground wire in the field coil connector needs to come out and be replaced with a +12V supply from the ignition circuit. The xs400sg/sh/SJ wiring diagram can be a guide.

I haven't had to make this modification myself. Definitely go back to the wiring diagrams and understand what's going on before making changes.
I know someone recently did switch their field coil wiring around to accommodate a different regulator. Don't recall who it was or how much detail they went into.

 

[BBS360]

You'll also most likely have to redo the regulator/rectifier connector.

 

[drewpy]

still buy new
http://www.electrexworld.co.uk/acatalog/RR38.html
RR38 maybe on chineses sites too, but one i got for the FZ was slightly faulty and I was lucky it semi worked

still need to check your wiring for tyhe bike as Yamaha was experimenting on the best tech of the time

 

[Supercoyote]

Hmmm. I already stuck with the points to avoid rewiring for electric ignition despite having the trigger plate, rotor and stator from such a bike. Wiring is not my strong suite, and there's nothing worse than buying a bike that has been sloppily had the wiring harness chopped up. It's too bad, the chinese sites have the DOHC rectifiers for 25$, but for the SOHC they jump up to 100$.

 

[BBS360]

The regulator change doesn't take much rewiring, just adding the positive line to the field coil connector.
Rewiring a 360 harness for electronic ignition would definitely be some work though.