GSX-R Hand Controls + Honda CB750 Wiring Harness

rs_ss350

Active Member
Hi all,

I've done a GSX-R front end conversion and am planning to keep the GSX-R hand controls. Has anyone done this? I'm in the process of connecting the Honda wiring to the GSX-R right hand control containing the brake switch, starter button, and kill switch. Has anyone done this? In the wiring diagrams I am seeing slight differences in the kill switch wiring and i'm wondering how to rectify that. There are 7 wires in the honda side, and 7 in the gsxr side, but it looks like two of the GXR wires are for UK lighting applications only, so there's two wires from the honda side i need to figure out what to do with. Has anyone done this before? Any advice? I'm kind of lost when it comes to electrical.

Thanks!
Rob
 
If your that lost it will be easier to sell te Suzuki stuff and get some Honda switches, at least the colours match up.
It's a simple swap, your asking for someone to tell you what to do - I just told you
 
Open switches, see what colour wires go where, write it down and compare Honda and Suzuki
Suzuki use Black with white trace for ground, it can make life difficult as Honda uses black with white trace for ignition and green for ground.
I know there are lists of main colours used by manufacturers, (I've posted some of them) Suzuki, Honda and Yamaha use Red as main power feed before ignition switch then orange,(S) black (H) or brown(Y) from switch to fuse box. Kawasaki used to use White, sometimes both ways so I don't use any Kawasaki parts if I can possibly avoid them.
Nothing wrong with wanting to learn but generally not a good idea if you don't have any experience of building BSA bikes
(Bits Stuck Anywhere ;D )
 
Another option is to skip the diagrams complete and just use a multimeter to test all the connections.

For example, when attempting to discover the wire purposes on the right hand control, your steps might look something like this:
1.) Set the multimeter to read resistance (200Ω setting is good).
2.) Decide on a function to discover (we'll start with the kill switch)
3.) Turn the kill switch to the 'run' position. In a bike with points or TCI ignition, this will mean we're looking for continuity. In a bike with a magneto or CDI ignition, we're looking for lack of continuity.
4.) Pick one of the wires (doesn't matter which) and connect it (alligator clips are nice, but you can hold it with your hands, too) to one of the probes on the multimeter (doesn't matter which).
5.) Using the opposite probe on the meter, start touching all of the other wires, one by one. Assuming we're work on a bike with points or TCI (95% of street bikes will fall into this category), we're looking for a reading on the meter close to zero. You will be able to see the meter switch from OL to something like 0.4.
6.) When you've found a match, switch the kill switch to off and see if the meter shows Open Line again.
7.) If so, you've the two wires associated with the kill switch. If the meter is still showing a reading (instead of Open Line) after turning the switch off, keep looking.
8.) Now that you've found the two wires, you might need to determine which is positive and which is negative. This is more likely to be an issue with modern controls because it's common for manufacturers to use a single input for power and route it, internally, into several outputs. The power wire might be used for one, many, or all of the following: Brake switch, kill switch, starter button.
9.) Determine which of the two wires you think is a power wire. Colors might help with this. Most manufacturers have a "flavor" of wire they use for power. Honda uses black as a primary color for power wires, so solid black, black/white, black/red, etc are all common colors to find on powered circuits on a Honda. Yamaha uses brown, blue, and/or red/white depending on the year. Suzuki generally uses orange, and Kawasaki can bite my ass.
10.) Using your suspected power wire from the previous step, repeat your tests checking against other wires in the bundle. For instance, let's assume you suspect that the orange/white wire is the power wire on GSXR controls (you'd be correct, but let's prove it). With one probe of the multimeter on the orange/white wire, check the next wire in the bundle and start pressing buttons or pulling levers and see if you can get your meter to show continuity. Depending on the year of your controls, you may find that the yellow/green wire will also show continuity when pressing the starter button. This is because the power coming in from the orange/white wire is used for both the kill switch and the starter button.

Expect to spend an hour or more doing these tests, but when you're done you should have a clear understanding of what is what on your controls and no diagram will be needed (at least not for the controls).
 
Thanks guys - I appreciate all this info! This is indeed my first build, but I would like to build more "BSA" bikes after this one, so learning as much as possible from the experts here. Thanks again :)
 
If your building to sell, you have to make sure bike is minimum of 100% right as you will probably have some wannabe with more cash than sense or bike knowledge. If they then kill themselves because they did something stupid, sad but 'oh well'.
If they get killed because YOU did something stupid , different issue
That was the biggest issue I had with this site when I first found out about it, too many 'Internet Experts' with limited to zero actual knowledge or experience
After deleting over 1200 posts I thought it may be better to educate people.
Now, you will find many members telling you what is and isn't safe, often repeating things I told them 8~9 yrs ago (particularly on wheels, brakes, tyres)
There are a couple of fantastic bikes built by accident, the modifications needed just to make bike ridable led to major design changes and better quality work.
 
I'm building this bike to ride, and I have another one with a dead engine sitting waiting to be built. Also building to build because I enjoy the work. Used to wrench on old cars, now I'm enjoying the bikes. I do realize I need to make sure this bike is 100% safe for ME to ride because I'd really prefer not to die on this one. I do my work at a community bike shop with many professional mechanics present, and I will pay one to inspect my work and make sure all is well before i go do anything stupid... but maybe i'm already doing something stupid by building it myself!
 
Nah, really stupid is paying someone else to build what you want and not knowing if they are actually doing things properly.
Doesn't matter how much of a 'Big Name' you are if bikes are 'not your thing' Many 'custom car builders' have tried bike building, most a total disaster. I won't name names, but, I could ;)
If your building for yourself, you will get more help if you need it.
One thing though, I used to train 'professional technicians' they vary in ability and ethics, sound like you may have a few good ones, the real good ones may piss you off but wil prevent any noticeable F.up's before you go too far, they should know that the more people who kill themselves on bikes, the greater chance of real restrictive legislation which could affect them directly. I'm from Britain so I've seen it happen over there
All for now,

PJ
 
OK, thanks to your tips and the diagrams for reference, I've got this mostly figured out. A couple things I'm stuck on. For the turn signals, I have matched up the wires that go to the relay (light blue on the gsxr side, gray on the honda side) and the left and right indicators. When I activate the turn signal, the light comes on, but it doesn't flash. Should I assume it's the relay? Is there a way to test the relay? Is there something else I should look at? There's a green/white wire that also comes out of the relay, and the wire is in the connector for the honda side, but doesn't connect to anything on the other connector... you can see it seem to terminate at the connector for the left hand controls.

Here's the CB diagram if anyone wants to look.
http://www.cb750c.com/publicdocs/Color_Wiring_Diag/CB750K_81-82_Wiring_Diagram.pdf

Also, there's one extra wire from the honda side I haven't fond a place for. It's brown/white. in the honda diagram, it seems to give power to the turn signals when the ignition switch is on. the original honda signal lights seem to have two power inputs (in the diagram: orange/white when power switched on, and solid orange when the turn signal is switched on). My new turn signals only have one input wire and a ground wire. I assume I can leave this brown/white not connected here? Or should it be connecting to the single input wire as well? Will this affect the functionality of the turn signal...

Thanks in advance for any tips, still learning here.
 
Relay would be the most likely culprit (especially if you're using the stock relay with LED bulbs). For a standard flasher relay, they work by running enough power through them to heat up and deflect a small wire. When the wire is deflected by the heat, the circuit is broken and the signals turn off. With no power running through it, the wire cools down and returns to its original location; activating the circuit once again. With an LED upgrade, the newer style lights don't use enough power to cause the relay's wire to heat up enough to deflect; so you end up with non-flashing turn signals or signals that flash very quickly. A new LED-compatible flasher relay is the recommended method for fixing the issue (we have one on our website for $8 and free shipping in the USA), though load resistors will also work (but they do so by sucking extra power from the system, defeating the point in using the lower wattage LED bulbs).

For the brown/white wire, from the stock controls, this is used to light up the gauge backlights and it also routed through the ignition switch, to the brown wire, to light up the tail light. If you plug the brown/white in the harness directly into a black wire in the harness you can have the gauge back lights and tail light on whenever the bike is.
 
One more question, For the turn indicator lights, I'm using LEDs that are built into the top triple tree from cognito. Will I need the diode to that you have on the site too?
 
If you only have one indicator for both directions, yes. If you have separate left and right indicators, then no.
 
It's easier to just get a new flasher relay, the power resistors are a total waste of money in my opinion and often cost as much as replacing relay with a new style 'timer' type.
I have a 'boxful' of old style bi-metallic relays, some brand new in boxes. May use them on truck if the original ever fails but it's unlikely I'll ever use them on a 'vintage' bike (I don't do 10/10 restorations ;) )
It's possible to open some flasher relays up and fit a 1/2w power resistor inside but hardly worth the effort
 
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