Simple Motorcycle Wiring Diagram for Choppers and Cafe Racers

I get a lot of questions about wiring motorcycles. Sometimes people are just trying to fix their blinkers and aren’t familiar with how motorcycle electrics work – but more often than not I get requests about trimming down electronics for custom riders.

An essential part of building any sort of chopper, bobber, cafe racer, brat bike, or rat rod is getting rid of all the unnecessary items. These days I just grab my wire snips and start trimming away with no regard for common sense and caution – but if you are working with your first wiring loom I’m going to try and give you some guidance right now.

You might have checked the wiring diagram for your bike already and seen something like this:

The above diagram is from a Honda CB750 Custom dual cam bike. Lots of 70’s and 80’s bikes will look the same, especially the four cylinders.

If you are trying to build a stripped down bike there is a lot going on that you don’t need. A lot of the controls can be removed, blinkers, gauges and indicators, relays and switches. It doesn’t take a whole lot of wiring to keep a bike on the road, especially if you don’t want to cater to the law word for word. By trimming down the wiring you’ll be saving complexity, saving weight, and cleaning up the look of your bike.

Below is a generic wiring diagram I whipped up that can be used as a guideline. I tried not to tailor it specifically to any particular model of bike, and I tried to make it as easy to understand as possible – but really any 70’s and early 80’s model bike with carbs will adapt to this diagram quite well. This diagram is setup to run a headlight and brake light, keep your battery charged, and have a keyed ignition. Personally, I sometimes strip my bikes even further, but I’ll mention that further down the page.

When working on your existing wiring loom it is best not to just start cutting wildly (like I do!) but to be very careful. Inside your headlight is where much of the wiring converges, so is a good place to start. Remove your headlight and start trimming back the sheaths. Slice back the sheaths of the wiring loom as far as possible to expose the wires inside.

If this is your first electronics exploration, start with something easier. Pick a fixed item you’d like to remove and trace the wires. An easy starting point is the blinkers. To remove your blinkers, unbolt them one at a time, then trace the wires through the cut open sheath. The grounding wire will most likely be shared with your headlight and gauges depending on the bike, so don’t trace the black wire, just unplug it. But, you should be able to follow the positive lead from each blinker all the way to the flasher relay which will be near the battery and rectifier under the seat. You can remove all of this wiring, the relay, and of course the blinkers.

Keep going one item at a time. You should DEFINITELY be using a volt meter. IF YOU DO NOT HAVE A VOLT METER GO BUY ONE NOW! You can buy a cheap volt meter from Harbor Freight or Northern Tool for around $10 that will look something like this:

It will do everything you need. Or if you are a stickler for high quality tools like I am you can spring for something like a Craftsman Multimeter for around $50-60. This is what I use – though I must state, I only use 10% of what this device is capable of.

It should be noted that my diagram caters to my desires – I generally remove the switch controls on the left side of the handlebars, and the ones on the right if possible (often times the throttle housing and switches are a single unit). I replace my controls with simple switches picked up from radio-shack, and mount them where ever pleases me at the time. Sometimes I’ll make a little plate to mount them on the dash:

Or sometimes I’ll just stick them to the headstock, or under the seat so they are out of the way completely. The above KZ440 I didn’t remove a lot from. In this picture I had one switch overriding the keyed ignition, and another activating the starter. It was kind of a weird setup, but the only photo I have handy.

But anyway…..

When removing things you always want to make sure they are either not being utilized or serve no essential purpose. If you have the bike running and you’re watching voltage on a particular item (for example: a neutral switch), you’ll understand when it’s being used and when it isn’t and this will help you make a decision of whether or not it should be cut out.

I will usually ditch the:

  • Gauges
  • Ignition
  • Blinkers and Flasher relay
  • Left controls (right side depending on throttle setup)
  • Side stand switch
  • Oil pressure switch
  • Neutral switch
  • Maybe a front brake switch depending on the type
  • License plate light

My general goal isn’t to be legal. You know what I’m after.

There is a lot more involved with doing a clean wiring trim than what I’ve mentioned here, but hopefully this helps push you in the right direction. If you have questions, please ask them either here in the comments or on my new Motorcycle Repair Forums. I do my best to help out everyone who posts.

Also – for some of you who are more adventurous and are looking for a hardcore diagram for modifying a kickstart only bike to run sans battery – have a looky:

I won’t explain the above right here right now – but if you’re looking to go as low profile as possible and have questions, please let me know. On many bikes you’ll need to introduce a capacitor or two and possibly a particular regulator unit.

Cheers!

-Evan

ADDENDUM:

A reader recently had a very note worthy comment. My diagrams above have the brake light controlled by the same switchable power source as the headlight. This means that you must turn on the headlight for the brake light to be active. While I tend to like this setup – it isn’t necessarily the safest. If you forget to turn on your lights, your brake light won’t work. Hans graciously sent me an edited version of my diagram with the adjustment on it. Have a look:


ef

By ef

Hey, I'm Evan and this is one of my motorcycle sites. You can find more about me on my homepage, or visit me on Google Plus: +Evan Fell

218 comments

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  2. Don, I’m doing the very same thing. Retiring in a few years with plans to rebuild/cafe some old bikes to keep me active. How’s your rd project coming? I have a DS7 250, 1971.

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  6. I need help with my 85 V twin 500 Honda I can’t find a CDI boxes and I want to know if I can run off with my pickup and what do I need to do to get it running I got the bike with no CDI box please help I’m going crazy

    [Reply]

  7. I need help is anybody out there who can wire a xv1600 year 1999 im in mess
    if there is contact by email a.s.a.p please

    [Reply]

  8. hi john here you said can use the wiring diagrams which I’ve look at will they work xv1600 because of throttle sensor or can we do a way with that do we need that help can just wire it from you diagrams

    [Reply]

  9. I have a 1978 honda cb 750 k8 ive been interested n doing the same with my project cafe racer its my first project as a full time single parent of 4 i have very lil time to look into this my self an studie up on it if you could point me the right direction with this veery much appricated every lil bit of help is like takeing a mile for me … an ne info on hooking up a rec/reg n 1 with cdi ign boxes would b much help as well thank u….

    [Reply]

  10. Hi, I am trying to get a wiring diagram for my yamaha dragstar 650 1997, All I need is to wire up spot
    lights to the bike as anybody got a diagram for this thanks, Frank.

    [Reply]

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  12. How do you test or know which wires to use on coil pickup to wire to coil
    Got two pickup coil with 2 wires each.

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  13. what gauges for different acc’s? Lights, horn turn siggs, starter. I have a 91 sport I have stripped and reworked. Thanks Garz

    [Reply]

  14. I have a 1977 Honda4 800.6 I am putting a motor on a go-kart eliminating just about all wiring got ahead of myself I have two coils on it one with the yellow wire and a white and black wire the other one has a blue wire and a white and black wire which ones are the ground and where do I plug the hot wires into .
    that’s basically the only wiring I’m going to have

    [Reply]

  15. I have the complete frame of the 1977 Honda 4 i believe it is 750I was told it was $800 but its only 750 cc .it has good gas tank fenders Forks shocks tires rims brakes the wiring that is cut in a million pieces I just need the motor and exhaust chain and rear sprocketclean body no title good seat. Ifsomebody could help me out on how to wire up the coils after bypassing the wiring harness you can have it.

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  16. Need help in wiring up 82 gs1100 headlight. The three yellow wire coming off of the stator. I would also like to only run a speedo and delete everything else for a clean look. Any help, I could surely use thanks ever so much.

    [Reply]

  17. Pingback: Simple Cafe | Home
  18. Wiring a ’74 CB125, hoping to go battery-less, use 12v accessories (headlight/tail light/ neutral light…but kind of indifferent on the neutral light).

    It is kickstart only, but does have an ignition, which I am keeping. I am very new to wiring, but have read that on this particular bike, you can run a capacitor in place of the battery (which was 6v stock). Several people who have done this said they ditched the regulator and just had a cheap radio shack rectifier (which I purchased). One person also said only a 15 amp fuse was needed. Might there be a diagram, video, or step-by-step that could walk me through this thing? Thanks!

    [Reply]

  19. Someone gave me a 93 virago the owner was replacing the wiring harness but he passed away before it was finished where would a good place to start be for someone who is a beginner

    [Reply]

  20. I have a xv 400 Virago that I bought in pieces.

    So far I have figured that the loom coming from the front splits at the seat -the right hand side goes to the battery ( red terminal) and the left hand side goes to the regulator( black terminal)

    I still need to find how the negative ground( which comes out of the loom above the engine )is attached to the engine
    Will let you know How I progress if you are interested.

    regards
    alan

    [Reply]

  21. Yeah man same here, did you ever figure it out. I’m trying to build a harness for a 1983 cb650 and I can get It to fire, I think I may not have my igniter box or coils wired correctly.

    [Reply]

  22. What I am going to try to do is take the ignition switch out and put in a new ignition switch out of a 1980 Suzuki GS750. I want to wire it up like a car, where you use the key to crank over the engine and bypass the start button. I have four wires coming out of the current ignition switch (red, brown, orange, and gray) and I’m not 100% sure which is what, I don’t have a battery in it yet to test this stuff out. The ignition switch I purchased is marine quality with five posts B, G, M, L, and S. With no schematic on the packaging I am assuming it stands for Battery, Ground, Magneto, Lights and Starter. Is there anyone out there that can assist me with how to wire this bad boy up?

    [Reply]

  23. I have a 82. 1100cc a-1 kaw an need to know why my part coil isn’t getting ful voltage is changed coils an it still isn’t getting g full voltage

    [Reply]

  24. I’d like to do bare minimum simplified electronics on my 1980’s Yamaha XS250. Hoping it will make it more reliable and easier to maintain.

    [Reply]

  25. Hey. I’m working on a 1973 CB450 kick start only – headlight and taillight/brake light only. Do you have any diagrams for this setup? I plan on either a small battery or no battery and ripping out the starter.

    [Reply]

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  32. I have a 1967 HD sportster with a generator , no magneto. Ive put in a battery and distributor with points . Have only head and tail light and a voltage regulator . Can you give me some insight on how to wire this bike. Thank You Ken Taylor

    [Reply]

  33. Gotta say, this is exactly what i’m heading towards, by stipping out my existing, rather bodged loom, and doing away with all the switch controls, indicators etc etc. However, i’m not sure where my CDI would fit into this? Any suggestions please. Thanks

    [Reply]

  34. Hi Evan, I have a 1971 CB350 stripped down cafe style and sans the starter. Looking to do the basic wiring with no battery. Also thinking about ditching some older things like points, etc. Is electronic ignition the way to go if still doing kick start?

    I actually have a really nice full harness but may need to go with something else if I’m starting from scratch. So if I do that and have all the original stock parts what is the parts list for doing the kick start only diagram?

    [Reply]

  35. I have a 1988 yamaha virago 1100cc.I want my wiring as simple as i can make it. also, what do i do about the igniter? any help would be appreaciated. thanks.

    [Reply]

  36. Is it possible to get a custom wiring diagram for a 1982 kz1000j ?
    Using an Antigravity lithium battery, head and tail light, starter switch ect

    [Reply]

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