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:
Excellent diagrams! I am working on a 1983 Kawasaki gpz 1100 and I will definitely use your diagram. I have one question though: where would I place the CDI? I just bought a new DYNA 2000 and would like to use it.
Thanks for your invaluable information.
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I HAVE A 78 CM400 TRYING TO REWIRE IT AND NEED HELP ALL I WANT IS HEAD LIGHT,TAIL LIGHT,BRAKE LIGHT AND INGNITION SWITCH ….ALSO DONT WANT TO RUN A BATT.
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hey whats up i need some info . im rebuilding a 69 benelli its a total rebuild no harness at all all that is on the bike is points,coils, genie,battery,regulatory,headlight,tail light and brake switch. this is kick only i plan on using switches for points and accessories so any help or ideas would be great
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Hey Evan,
I was wondering where you got that cargo rack or where you think I could find one for the 74 Honda CB 350 F. Please let me know if you can help me out. I want to be able to carry a passenger and cargo at the same time.
Thanks,
Brandon
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got a 80 xs1100 bobbing it will only run with starter engaged any ideas?
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got a 80 xs1100 will only run with starter engaged any ideas?
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Evan,
Amazing site, definitely got me in the right direction.
I’ve got an 82 Honda CM450 that I’m trying to bob out and make as minimal as possible. Looking for a wiring diagram (and parts required) to get started. I’m looking to do a kickstart only with just a head light and tail/brake light and no battery, plus kill switch.
Your motorycle with no battery diagram above seems like what I’m going for, but I’ve been told I need to do a magneto/generator and capicitor setup. Any advice/diagram for this setup?
Again, just looking to go as simple as possible.
Thanks
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will this wiring diagram work on my 1980 Honda 650.. thanks
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What gauge wiring is used where? (or how do i determine that) I’m having a real problem attempting to find this info. As u can guess, I’m not an EE.
Thanks
Matt.
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nice site i understand the diagrams, but being a plumber my one question is what size wire. i have and old 69 softtail harley i am tring to save from the grave andi want to chop a ;ittle here and there. just need a little help. THANKS
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Hi, this is great work, thank you very much. I would like to ask some more questions about the battery free diagram if you have the time.
I have a bobbed ’86 450 Rebel that I love, and I would very much like to go kickstart + battery free on her.
Do you have advice for that year and model?
Thanks!
– J
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ghafeez Reply:
February 22nd, 2013 at 7:08 pm
Hey I just bought a cmx450 and im redoing the wiring, i know your comment was from a few years ago but I was wondering if you ever acheived what you wanted and how? if not what way did you do it and with what diagram? A replie would be greatly appreciated.
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do i need the pulse generator
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I have a 1978 CB750 that was running great. I I Rinsed off the lower half of the frame and wheels with light spray and will not start since. I have checked all of the fuses and seems there is no spark from the coils. Any suggestions, has really become a challenge.
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Les Reply:
February 25th, 2012 at 8:36 am
@chuck
All your answers are here.
http://forums.sohc4.net
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That last wiring diagram. Remove the break light switch and rename brakelight to taillight and it works.
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hey evan, please help me out. im 19 and just got into bikes and was blessed with a 1975 honda cl360, and iv just been wrenching at this bike day and night and finally hit a wall. to break this down i completely cut all the wiring from the right control handle bar (on/off,electric start,light on/off) out and disconnected all the wiring from the main harness. and left the control housing connected for throttle and brake still. but my problem is my engine wont run..? all els electricals work and battery fully charged…obviously i cant elctric start but kick start isnt working for me either. does any of the electricals from the right controls need to be plugged in in order for the engine to run or is there any other way around this. say maybe jumping the wires as i was advised ? or would i have to buy and plug in a complete right control side for my bike ? i really just want run the bike without the right side controls/wiring/ect period. i just dont know how….please help me man. thankyou !
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WOW, great write-up!! I’m currently hollow-modding a 1989 TW200 and your explanation and bare-bones wiring diagram will help me thin the herd of wires running up into the headlamp area.
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i have a 75 yamaha dt250 no lights,blinkers or battery just want kick start on/off toggle have 4 wires coming out of engine looks like only one wire to cdi where do i go with other wires what do i need and where do i get it. thanks
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can i run my 1980 cm400 with a capacitor instead of the battery,was looking at a battery eleminator system like the ones for triumph’s,my bike as a kickstarter,thanks
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paully Reply:
April 20th, 2012 at 3:13 am
check out my reply it should help you. i bought a sparky on ebay its for triumph but it will work as long as you have a magnetized system i believe. but anyways search battery eliminator on ebay and its called sparky it has all you need in one unit. hope that helps
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i am chopping a1981 cm 400 honda ineed to know how to make it ron with electronie ignition looks like if you anser all these other peopel you are dedaketed.
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i am chopping acm400 honda.ineed to know how to wire it useing theelectronic ignition on the bike rick
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I need a simplified diagram for an 81 yamaha xj 650, electronic ignition
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I bought a sparky battery eliminator(they say its for triumph) but i installed it on my honda cl350 per this diagram and it works. so i want to say a big thanks to evan fell. you are a God send! and to all the guys on here wondering what to use to connect directly from your stator. its called a sparky and i got it on ebay for 60 bucks. it does everything you need to not have a battery, rectifier/capasitor ect.. again many thanks i had no idea how to hook it up before i saw this site. and most sites told me to just run a battery and give up. i had already bought the sparky and was determined to make it work. you rock!!
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Love the wiring diagrams. just stripped down a Yamaha XS650 and getting ready to re-wire. I wanted to cut down on the size of the battery to conserve space, weight, etc. I am using a headlight and one rear running/brake light. Its a kick start bike with points ignition. How small of a battery can i go with ??
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Oh mate, what a bloody lifesaver you are!!! I live on Samui, an island in the Gulf of Thailand, and have a chopped Honda super four. I am no electrician, and the bike’s wiring is a nightmare that I have been struggling with for months. With your info I can now scrap the whole mess and start from scratch.. bloody brilliant! Thank you Evan.
Just one question… my ignition/key start is from a car, and so also does away with the seperate starter button. So how would the wiring look for that?
Thanks for sharing your knowledge and experience Evan… Alan
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I have a 1980 suzuki 550. The starter has a brown black and green wire comeing from it. What do these mean and how do I wire a momentary switch to it?
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Hi there i used this wirring diagram on my cb360t chopper and workd great than slowly fell apart. So i put new coils in by mikexs and new boots but my bike will only run without the condencer?????????????? Weard And it has weak spark on left side untill around 3000 rpm than spark jumps up and clears up. Forgot to mention one hell of a time trying to start. Any ideas im stumped Talked to atleast 50 or so people and no idea. Thanks man
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jason Reply:
June 27th, 2012 at 7:48 pm
had almost same issue sounds like your points are either off a bit or a bad condenser i changed mine and it works way better will it bog or pop or spit any thing like that and did you feel the muffs to see if same heat from both
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jason Reply:
June 27th, 2012 at 7:49 pm
sorry didnt read properly condenser is probally bad put new ones on should solve it also set gap and timing
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What gage wire should I use for the rewiring?
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man thank you,got a 1983 HONDA ngt/hwk in carport that only got to ride few times n quit, been there two months or more.finely got it to turn over,fuse box got hot,back to square one,I think it,s got to be wire,s.anyways while I was looking for parts found a 1983 HONDA 500/550 German metric,look,s like W.W.II bike. it has cafe seat,it is complete,rough but complete!my question is what its worth,I am thinking about going back after it,thought it was cool,n can get it dirt cheap.cannot find any info anywhere on it.THANKS AGAIN!!!!!!
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Hey i would really like to learn how to do the kickstart only wiring on my bike in a bit more detail i have a 75 cb360t any help would be great thank you.
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Hello, this is a great site. I am looking for the most basic wiring diagram I can find specific to a 78 gs 550 (toggle switch for bike, toggle switch for lights). I am also a little concerned with the wiring to the coils… I wasn’t sure if the cb750 schematic would work as this bike has a seperate regulator and rectifier. Is the regulator and rectifier on this system designed to be set up only one way? Or can I adapt these parts to a schematic above. I have removed the electronic start. I have a little electrical experience as I repair wind turbines. Thanks.
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just about the same promblem as shannon . I put a combanation reg-rec , on my 1975 cb 750. As far as i can tell the only wires you use are three yellow one white @ black. I want to use a 12v battery off my drill to power it . will it work ?
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Like everyone else, I would like to thank you, great site. Now, don’t the spark units on these bikes act in place of a vacuum advance? Should I expect to have to adjust the timing a degree or two?
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Hey,
Building my second bike and decided to do the wiring myself. I want to keep blinkers. Think i could get a version of this with the blinkers added. I Think i might could do it but i don’t wanted to make sure i had something to look at.
Thanks
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hi im running a 82gs 1100g i have the cdi ignitor box i was wonderi g could this adapt to my bike my wiring was shot and i to like the naked look only the essentials i am having a hard time with this one for some reason
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Thank you so much for the website and info, i just cut most of the wiring out of my ’82 450 nighthawk to attempt a brat bike. after cutting 95% out and walking away a few time your diagram gave me the ah ha moment i needed to get it to turn over. thanks again.
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Thank you very much for your schematic. I just picked up an 81 xs1100 sans wiring, but seeing as how it is a bobber project that is fine. I am brand new to fixing up bikes and electrical in general though. On your diagram it shows the wires running from the coils to the points or pickup and then to a ground. What exactly are points/pickups? Other than that it looks very simple. I am also not sure if the rectifier plugs directly into the stator, or will I need to splice the wires together?
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can any one help me i picked up a honda cm400 realy cheap and am doing a odlschool bobber and i want to get rid of all the crap under the seat i was told by 2 shops that it cant be done and keep it running its a 1980 model is this true?
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So I a redoing an xs1100 and I am not an expert with wiring. I have all the main stuff wired up, but I am not sure if that is everything I need to do based off your diagram. You mentioned I might need some resistors added, do you know which ones/where?
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This is as simple as it gets
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Alan Reply:
November 24th, 2012 at 4:06 am
Well I’m not to sure on pickup coils for my 81 750 I took the harness a little thinner than your normal rider .but it doesn’t look like the diagram at all still too many wires. How do I know what is what
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hey there i followed your wiring diagram with no battery and im not getting any spark to my bike when i kick it over was wondering if you could give me any input.. i have a 81 xs400 heritage special. thanks!
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I need a little help with wiring. I am a first timer trying to build a cafe racer. I re-located the regulator/rectifier , the starter relay solenoid and the battery under the seat cowel. It turns out that my starter is no good. I was told that you didn’t need the starter solenoid if you didn’t have a starter. Do you have a diagram for wiring my cb360t with keeping the battery and all signals and ditching the starter and starter solenoid? I tried wiring it on my own with no success. Do I need in line fuses? If you can send any info or recommendations, it would be greatly appreciated. Thanks
Ian
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You might have opened up my eyes right now with this thx
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so with this simple wiring dia i dont the spark units right go from the pulse unit to the coils?
tks dan
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I have a 95 1400cc Suzuki intruder someone put apehangers on it and changed the wireing on it instead of having the stock push button it had a radio shack button in the hole, the old button must have burned out.Anyway the one from radio shack burned out shortly after I bought the bike so I dicided to put an old harly push button on it.It worked three times one right after another I must have over heated something because I lost all power. So I pulled the seat off to check the fuses which I really dont have a clue look like & found a burned wire going into the black igniter box. I pulled the book out and read about auto compresion releases & still dont know what or why I dont have power to anything or what the igniter box does could you please help me Im not as stupid as I sound maybe? but when it comes to electricity pretty ignorant.Thanks for any help at all. Dart
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