Instructions and diagrams for re-wiring your motorcycle.
Hopefully you’ve seen our post on what the electrical components do in your custom bike, or how to pick the right cafe racer parts. This article will show you step by step how to hook it all up and get your Café Racer or Bobber firing!
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If you’ve read our “how to build a café racer” blog the wiring should be one of the final steps on your build. I like to split this job in 2, you have a running circuit and your accessories circuit, with 2 separate diagrams. This makes the drawings simpler and if anything goes wrong it’s easier to trace the problem.
Before you think about wiring, mount everything on your bike from coils to your lights and speedo.
Start by mounting your battery, and figuring out where your electrics tray will go. That should house your
- starter relay
- Flasher unit
- Fuses or circuit breakers
Once that’s sorted mount the Reg/Rec either underneath or next to the battery. It needs airflow as it gets warm, so DO NOT put it in a cramped spot that’s fully enclosed.
Now you’re ready to start wiring. Some people prefer to run 1 wire the length of the bike and tap off for the active wires, in my mind this way tends to lead to a lot of joins and if that 1 wire has an issue, your bike is going to have big problems.
I like to use a Terminal strip and join all the positive wires in the electrics tray. I separate the terminals into sections
- Charging circuit
I also always draw my wiring diagram, but I’m good with electrics so use mine to save you some time!
Get the PDF’s here. Wiring Diagram Download
Before you get going, make sure you use quality connectors or solder joints and heat shrink your connections. With that done, let’s start with the charging/running circuit.
- Run a black lead from your battery –ve to a clean bare metal part of the frame and bolt it on, this turns your whole frame into a ground. Also be sure to ground your engine/gearbox case at one point. Then run a red from the +ve to the starter coil. Connect the other side of your starter coil to the starter motor. This is done in heavy duty wire.
- Run a standard red 15A cable to the main fuse (20-30A) then to your key ignition. From the key ignition there will be 2 other cables; one goes to your charging circuit and coils, the other to a fuse for the lighting and accessories circuit (10-15A).
- Start finishing up your Running circuit, connect the 3 (normally yellow) wires from the stator to the reg/rec then connect the red to the battery +ve and the green to the –ve. Some bikes (Honda CB750s) will have extra cables to connect from the reg/rec to the coils. If not it will be included in the signal generator and CDI unit.
- Get your signal generator and CDI unit plugged in (or points), then run your blue coil trigger cables and connect the coils to your spark plugs.
That’s your charging and running circuit sorted, (the easy part) now work on finishing your lights and accessories. They’re already mounted up so the looming and connection is all that’s left.
- You’ll have to run a few wires from your electrics tray to the front of the bike. I use a Black “snake skin” to protect my wiring from damage and it looks a lot better than your standard plastic wrap or electrical tape. as a minimum you’ll need;
- 1 red active linked to the switches; headlight, brake, horn and starter
- 1 orange switch wire for your starter
- 1 pink switch wire from your flasher relay
- 1 green wire for rear left indicator
- 1 brown wire for rear right indicators
- 1 orange switch wire for the front brake switch
- 1 black ground wire
- Try to use solder connections on wire joins and good quality joiners for connection to switches and lights.
- Connect the positive cable to your switches; headlight , brake, horn and starter
- Connect the orange wire to the other side of the starter switch
- Connect the pink switch wire to the common terminal of the turn signal switch.
- The green and brown will terminate to the left and right sides of the switch, then connect those wires to your front indicator actives.
- You’ll have spare terminals left on the hi/lo beam switch, connect the blue + yellow straight from there to the light.
- Now hook up your signal lights if you have them in the speedo cluster or triple clamp. (Yellow for turn signal, blue for Hi beam, green for neutral.)
- Connect the purple from your horn switch to the horn.
- All of your accessories will need to have the black wires grounded. You can connect this to the frame at any point or join them all and run a wire back to the electrics tray.
- Now work from the rear of the bike back to the electrics tray (use snake skin here again). You’ll need;
- 1 red active wire for the rear brake switch, the running light, and the number plate light.
- 1 orange switch wire from the brake switch
- 1 green wire for rear left indicator
- 1 brown wire for rear right indicator
- 1 black earth wire
- Connect your red active to the brake switch and the orange to the other side, then run it to your brake light also.
- Connect the rest of your lights and finish off by grounding the neutrals (black)
- The final step is to use your terminal strip to connect it all together and wire in the flasher relay.
Now fire it up! I know there are simpler ways to wire a bike however in my experience, a little extra work here can save you heart ache if there is ever a problem. Simple fault finding is what I aim for.
I hope you’ve taken some good info away from this, again click here to download the PDF wiring diagrams I use for your own custom Café Racer, Bobber or Chopper project. Please leave me your comments below!
Thanks for taking the time,