katana wiring

•  '82/'83 wiring harnesses are not the same

•  Cannot interchange '82/'83 controls

• Cannot use a GS1100e stator or cover on Katana

•  Consider a head light relay setup

•  Oil light warning usually bad sending unit/connection
     Who doesn't love chasing down electrical gremlins? I don't. One of the major contributing factors to an ill performing bike is corroded contacts. Those bullet connectors are harbingers of corrosion. Oh yeh, over heated terminals as well, thanks to Suzuki's legendary poor charging system. Hopefully this page will help you with a few things. Make sure all your contacts are clean and don't expect to much from your thirty year old wiring harness.


     There are three phases (wires) coming from the stator and plugging in under your seat. Connect all three wires directly to the regulator bypassing the wire that goes up to the kill switch plug and back down again. It doesn't matter how you connect the wires as they do not have polarity or a particular order. Check the wiring diagram to get the job done.

     The 750cc, 1000cc and 1100cc Katanas all use a 750cc size stator and cannot accommodate an GS1100e stator. There is a diagram on the "Engine / Gearing page showing the size difference of the fly wheels. To use an 1100e stator you have to change the flywheel, the stator and the stator cover.

Although the big cats use a 750cc size stator, an actual 750cc stator is not a bolt in. The 750cc stator has its phase wires routed out the bottom of the cover so the wires will come up short, and the rubber seal on the wires does not reach its position to seal the cover. The 1000cc, and 1100cc stator wires are orientated at 3 O'clock. If you look at the stator covers, you will see bulge in the cover, 6 O'clock for the 750cc, 3 O'clock for the 1100.


     These old charging systems are not the best. I use Compufire 55402 regulator/rectifiers on my bikes. It is the only reg/rec I have found that doesn't cook my stator, and because of its heat dissipation properties I found a drop in my oil temperature as well. The stock regulator rectifier bakes the stator and boils the oil it sits in, that is why  your stator is black instead of brown.

They are not bolt on replacements because they are made for 3 Phase Harley Davidson applications but adapt well for the GS. Explain your application when and if you purchase. They are not cheap.

     If you are having problems with your charging system, there is a charging fault finding flow chart from Electrosport Motorcycle regulators/rectifiers below. Very helpful. Before I moved to the Compufire components, I upgraded the stock reg/rec to the electrosport.
charging fault


     Wondering if there is a better option than that old car battery your GS is carrying around? There is, I use Shorai lithium iron batteries. The stock battery is 14Ah @ 190 cold cranking amps, 5.5" x 3.5" x 6.5" and 4.6kg. The Shorai lithium replacement is 14Ah is under 1kg, 4.5" x 2.25" x 3.5" and has 210 cold cranking amps. The one I use is 18Ah, 270 cold cranking amps, 5.83" x 2.63" x 4.13" and 1.05kg.

     I take my battery out for the winter and just leave it in the basement at 13.6v and the voltage will stay there for 6 months. With proper maintenance the lithium has a claimed life of 8 years or more compared to the acids I replaced every 2.

Harness / Controls

     The 1982 and 1983 gs1100 katana do not have the exact same wiring harness. They have a different pin out placement for the white Molex  controller plug that resides under the seat beside the blue Molex controller plug. If you install 1983 controls on a 1982 katana, you are not going anywhere unless your pushing. Don't ask me how I know or how long it took me to find out why I only had power to my rear brake light and nothing else. The plug coming from the kill switch and the signal control have a different pinout than the harness of the other year.

     I am a resto-mod guy so like to upgrade many of the old parts. GSX-R controls are a nice upgrade. I have added hi-low pass and a headlight off switch by using late model GSXR controller. The kill switch is a very easy upgrade also. When using flatslide carbs you need to use a push/pull throttle which requires a slimmer kill switch assembly.
katana wiring diagram

Tachometer / Repair

     These stock unites are getting scarse. I like the SPA ($500.00) or Vapor ($150.00) clocks in place of the stock Katana instruments. If you want to try and repair your stock Katana speedometer, a friend of mine Joey Hong has put together an instructional how to you can see below.
speedo pinout
speedo repair
vapor wiring diagram
speedo wiring

Headlight / Signals

Headlight Relay

     Dim lights are bad for a bike. Usually with these old harnesses, there is much resistance in the system so by the time voltage reaches the headlight, there is not enough to burn it bright. A headlight relay hooked directly to the batter helps this. Read the "How To" .PDF file below and thank you Matchless for the contribution. Excellent instructional.

Signal Lights

     LED signals require a low load signal relay to work. LEDs do not have enough resistance to actuate the Katana relay.

     The signal control module on under the left side cover is not needed for the signals to work. It is part of the auto cancel system. If that is not working anyway, or you don't care about it, remove it and save some weight and room.
headlight relay


     I like to use the Dyna S ignition to replace the stock Katana ignition system. Another upgraded system is the Dyna 2000 which you can wire in completely bypassing your stock wiring harness. Since it is isolated, any faults you may have can be ruled out from your wiring harness. Below are the install guides for both and a trouble shooting guide for the Dyna S.
dyna 2000 install
dyna s install
dyna trouble shoot
Welcome to the Katana technical pages. This site is the result of my years of experience upgrading 1982 and 1983 GS750 / 1100 Katanas with wheels, suspension and brakes to more modern versions. The site also has other information of interest to both Katana and other GS owners.

There is a time and financial cost maintaining this site, and answering your many email questions. Would you consider selecting one of the options below to help offset my time and costs? I guarantee you, after years of searching forums, wasting money buying parts that don't fit and don't work, the information here will save you significant money, time and frustration, because everything on this site has been tested on my own bikes.

Have a look at the information, and if you truly feel you have not got at least a dollars worth of entertainment, inspiration or information, then I thank you for visiting and I hope you liked the bikes, and will come back.
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WARNING Posted on Friday, November 17, 2017
   Information on this site is my personal experiences and experiments with modifications. I am not a licensed mechanic. Any changes to handling, braking or anything else described on this site are for entertainment purposes only. I do not recommend that anyone make changes to their motorcycle without checking with a licensed professional.

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