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:
Im looking for any help on my wiring on my 1982 Suzuki GSL550. I would like to ditch everything except speedo, headlight, brake/plate light
[Reply]
Hey Evan,
thanks for posting this. Do you have any ideas how this might work with a ’79 CX500 Custom?
Stock it has a CDI unit, but I changed out the Stator from a G47 Stator to a G8 stator and got an Ignitech to replace the CDI.
Thanks in advance for the help,
blivy
[Reply]
I have a 1966-ish CB160 I am trying to get started. It is in decent shape, however it is not starting or spark. There are a few wires that seem to be loose and no battery. There is no stater on the bike eitther. I was wondering what wires I need to connect to get spark and begin trouble shooting. Needless to say I am new to the vintage bike scene but very excited.
Thank you –
[Reply]
I’m really loving the theme/design of your website. Do you ever run into any internet browser compatibility issues? A number of my blog audience have complained about my blog not operating correctly in Explorer but looks great in Opera. Do you have any ideas to help fix this issue?
[Reply]
I have kz440 custom hardtail. Has headlight break light key ignition that’s it , but keeps draining batt. Even when key is off. I can’t find a short n wires. What do I do? Very irritating.
[Reply]
Please help
[Reply]
I have a 1980 kz1000b4 and want to make kickstart only and run only the lights. What do i need to do to remove the battery system and basically all the wireing like the simple wire diagram
[Reply]
i would like to find a simplified wiring diagram for 1981 cb650 custom. would like to keep blinkers, horn, lights…have done a chopper in the past, but would like a schematic to follow…
[Reply]
Looking for a simple wire diagram to build a wire harness for a 1982 virago xv750 that is going to be cafe’d any and all will help.
[Reply]
I am bobbing my suzuki gs850gt. I have to reworded. All I want is headlight, brake light, turn signals, hi lo beam switch. Could you maybe do up wiring diagram that I could use as a guideline. Thank you.
[Reply]
These diagrams are super helpful!! Quick question though. I have a 75 CB360 that I want as small of a battery as possible on and my goal is to make it so I have only a key ignition with no start button (just kick start) with only front and rear lights with LEDs for turn signals. Is this even possible? Do I need a start switch with a key ignition? Thanks!
[Reply]
Hi Evan,
Thank you for this very helpful information. One item that I don’t seem to see anything about on this forum is changing to a smaller battery. I’ve seen a lot of stripped down bikes on the net that presumably still have a battery, but I can not find it in pics. Is there a way of replacing standard batteries with a much smaller battery? I’m rebuilding a 1981 CB900 custom based on a couple of CRD and Deus rebuilds. I want to simplify everything yet retain my electric starter. Any suggestions?
Thank you,
Mikael
Phoenix
[Reply]
Hello Evan,
I am working on a Yamaha XS250 1977. I am not so into the electrical stuff, so I need some help here?
I am building a cafe racer, but want to leave out as much as possible. So no turn signals, no battery (only using Kick starter). So it is just head and taillight. Do you have some sort of a wiring diagram for this? I heard that by removing the battery you will need a capacitor? But how does this work? And do I still need a starter switch? Please can you help me out?
Kind regards,
Jorge
The Netherlands (Europe)
[Reply]
Hey Evan,
I have a 1981 Yamaha 850xs Special(triple piston >.<) that I'm trying to bring back to life and customize!
Honestly, the number of pistons intimidated me just because I'm used to seeing either 2, or 4.
Can you please help me by showing me a diagram describing/illustrating how to wire 3 ignition coils on a motorcycle with three pistons so that it will run like it's supposed to?
My first motorcycle project!!!
I'm excited about getting it to run again! Thank you for showing the diagrams that you already have! It's inspiring for me.
Jacob
Plano, Texas
[Reply]
Jacob Reply:
August 31st, 2013 at 5:01 pm
Wait! Never mind! I figured it out! Thanks!
[Reply]
Hi. I have an ’81 KZ440LTD. I’ve cut, chopped and bobbed it out… but now I want to do more. I’m trying to simplify the wiring. I want to eliminate the button start and key, and have the whole starting system on a typical automotive turn-key. I’m lost on exactly what to wire to which…BATTERY +, IGNITION, STARTER and ACCESSORY. Any help would be greatly appreciated.
[Reply]
Thanks for your generic diagrams they have helped loads. I am in the process of building a Yamaha RD 250 air cooled cafe racer, the first of many for my retirement plan to keep me in the garage! It is kick start. I would like to run horn,headlight dipped+full beam with rear light, no indicators,rear+front brake light. It has generator/rectifier/regulator, points ignition with 2 coils, it will have a battery. Do you by any chance have a suitable diagram? Thankyou very much.
[Reply]
i have a kh550 and a ltd 550 inport. in boxes and i have got the wiring looms all in one box.
con someone let me have wiring diagram of the kh550z
ltd 550 to please
[Reply]
gentlem
there has never been a book for the beginner.5 wires come out of the sator , where do thay go,
[Reply]
your digram is the best ive seen so far ,wish you make a dvd ,maby electric is like spokeing a weel smiple when some explaines it.Good man, A FOOL WHO HIDS HIS FLOOLY IS BETTER THAN A WISE MAN THAT HIDES HIS WISDOM!
[Reply]
I have an 81 cb650. At first there was no power at all, so Ireplaced the solenoid . Now there is power but the neutral light stays on all the time even with the ignition switch off or even when its not in neutral. When I hit the start button the neutral light turns off and the oil light comes on but the starter doesn’t turn unless you jump it with a screwdriver. I’m not good with wiring so I hoped you could help me troubleshoot it.
[Reply]
I’m trying to sort through and simplify the wiring on a 1977 KZ750(points/single coil). What would be required to be kick only, no battery? Thanx!
[Reply]
I have a 2003 kawasaki vulcan 1300 classic need some help. can I do a bare minimum wiring job if the bike has fuel injection or do I need to consider swapping to a carburetor on the 1600
[Reply]
Evan,
I’m looking for a diagram for my ’02 Honda VT1100C. I want to simplify & eliminate some items like the kickstand switch, kill switch and eliminate the Honda hand grip control blocks.
I want the wiring to be simple like on my first bikes 1970 H-D FLH & ’78 Bonneville.
Please advise,
David
[Reply]
my bike dont have a electric starter. It will start without a battery. i need to know where to run the hot wire from the battery. I guess it runs the lights,The only lights will be head,tail and break lights.I want as little wires as possible.Its going to be a cafe racer. the man who had it before me and was doing the same thing i want to.He passed away and it was all apart in his basement when i got it.he stripped away all wires and the rest was in boxes.i havve it halfway running and together.after i get it all together i will take it apart and paint then put it back together and replace what neede replaceing.This is a long turm project because im disasbled and have very little money to do quickly. thanks for your time and any help will be great. Take & Care and thanks again!
[Reply]
Woul the first wireing diagram work on a 125 off road buggy? It has all the same componets but we cant get a spark because the wireing is all over the place but it has a rectifire coil everying thats is needed could i could copy this diagaram onto there and it would work? Or would it be a different story? One more thing it has a power wire coming off the starter solinoid but it also has another wire coming from the solinoid on the same terminal as the power wire that has a 10amp inline fuse from yor diagram i can see that is for lights? On the buggy therr is a splice furter up that we can get 12v from but when i spliced into that and hooked it up to the coil the fuse blew?
[Reply]
Ripping out every dang electrical wire off my 1983 kawasaki kz550 bobber and rewiring using this guide. Thanks!
[Reply]
This is an awesome write up. I am building a 84 bmw r80 chopper and need to get passed the electronic ignition set up that it has. do you happen to have any experience with these or suggestions on how to wire as simple and direct as possible. just looking for the basics to get the bike wired and on the road.
Thanks for your help.
[Reply]
I have a 1980 Yamaha maxim 650. My headlights come on when I turn the key but when I start it up they go off
[Reply]
wire diagram perfect but what gauge wire. THANKS
[Reply]
I have a 1980 cm400 t motor that I am turning into a go cart can you please help me with a wiring diagram that takes away everything but the ignition and the charging system so I can eliminate everything that is not needed
[Reply]
I read a lot of interesting posts here. Probably you spend a lot of time writing,
i know how to save you a lot of work, there is an online tool that creates unique, SEO friendly articles in seconds, just search
in google – laranitas free content source
[Reply]
How can I have brake lights and not tail lights !!!??? Sooo frustrated ! Any advice appreciated !!
[Reply]
I need a basic wiring diagram to hard wire a 1979 gs850 the bike basically has no wires on it atm it’s just a motor on a rolling Frame please help!!!!!
[Reply]
Hey great stuff here I’ve got a 76 kaWI 750 twin the starter is taken out and i want to make it kickstart only can you send me a wiring diagram with a battery that you would recommend
[Reply]
The Information here is so clear and helpful… However, I have 2002 dyna that I’ve stripped down and left only the most essential for the bike to run, my question is, how does the map sensor get wired? Could someone please explain how the wiring on that works?
[Reply]
I have cb 750 sohc 1979 have problem i only have one cilender firering i have spark is it a carb problem or somthing elts
[Reply]
When you say you like to remove the ignition, do you mean the stock ignition switch or the electronic ignition box?
Thanks
1985 Yamaha XJ700n
[Reply]
These diagrams are fantastic. I will be using them on most of my mopeds.
[Reply]
Superb, what a weblog it is! This webpage provides valuable
information to us, keep it up.
[Reply]
Hi, Brent! Yes the stator has 5 wires. 3 green ones you can connect in any order too the 3 yellow on the rectifire and a green wich is ground too frame and black too battery.
[Reply]
I’ve got a 1956 Triumph 6T mostly done but for paint. I installed a Hunt pre-unit triumph magneto and I’m not sure that I need the charging system, just to install a capacitor. In addition I have a 2007 Royal Enfield with way too much electrical stuff (and other junk weighing the bike down) which I’d like to remove. The bike is kick optional so I want to make it kick only. I’d love to pitch the “trafficators” but I think Missouri law has me keeping some sort of signal system as the bike had them originally. I know that if I build a bike from scratch (as I have done) I can be as simple as I can make it with only head/tail/brake/horn a requirement. I hope you can enlighten me about what I can pitch on the RE. Right now the electric start doesn’t and there are other non functioning electrics and I am intimidated by the bizarre wiring schematics I have come across. Thanks
Tom
[Reply]
Hi Evan! i have a honda ss50 1967 the headlight and backlight not work right.
When turn key on signal and brake light are work good
When the engine run the both headlight and backlight not work(swith to low or hight)but if i step on the brake both light are on.i dont know what happen to it.Can you give me an idea?
[Reply]
Evan! Hey. Quick question. I’m requiring my 82 cb900f. Neutral switch wire. Can I just cut and cap off the wire going into the starter motor bay? Will that create a problem? Will I be able to start the bike in gear? Thanks huge.
[Reply]
many thanks just found this site very useful as I am building a stripped down 1985 Honda vt500 ed an I was wondering where to start got a good idea now do not be surprised if I ask some silly questions in the future ride safe d g c
[Reply]
Hey any tips for a Suzuki savage 650 I need to wire the bare bones and I can’t seem to find where to start??? HELP ME PLEASE!!!
[Reply]
am building a custom homemade 1200 sportster ,, have looked at many diagrams . yours simply put wins,, and will save me alot of time..many thxs….
[Reply]
Can i use the wiring without battery diagram for my 6v MZ TS- 150 ? Or should i leave the battery on ?
[Reply]
Yo bro if you could help me out i have a 1965 Triumph T120R Bonneville that i am turning into a bobber..
headlight (with hi/low toggle switch)
tailtight
rear break light switch
3 position key ignition switch
2 wire alternator
in line fuse (or 2?)
Pazon CS-2300 ignition
Emgo 24-72451 ignition coil w/electronic points ignition
Podtronics CS-4030 12v 200w single phase regulator rectifier w/capacitor
This will be a true stripped down bobber. I will even let you take her for a blast when its done.
Thanks, Pat Cooney pjcr6@yahoo.com
[Reply]
Hi there! I could have sworn I’ve been to this blog before but after checking through some of
the post I realized it’s new to me. Anyhow, I’m definitely glad I found it and
I’ll be bookmarking and checking back often!
[Reply]