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DIY Race Harness Questions

7K views 23 replies 8 participants last post by  Shane675 
#1 ·
Sure has been a long time since I posted here. With quarantine and all, and lack of forseeable track season, I decided to dig in to a custom race harness for the bike. The bike will not be seeing street riding at all, and I have been hacking away at a spare harness I bought a while back. All I need is the bare minimum to get the bike running for the track. I have several questions and I'm hoping someone on here will be able to help me out. I run attack triples, so the key/cylinder are loose and just zip tied to the fair stay, so getting rid of that would be a priority. I have also had terrible luck with the stock run switch and ignition switch (cost me at least 3 track days), so getting rid of those would be huge. The way the bike starts now is I turn the key to run position and then hit the ignition switch (the run toggle switch was removed after there was internal break found in the wire, so I just soldered them together).

I plan on keeping the "alarm" plug and having it accessible at the front of the bike (I have just the 4 wires that are jumpered together with how it comes). When I want to turn off the bike I'll just pull that plug to kill the bike.

Questions:

Are the fuses even necessary at this point? The bike will be running again at a bare minimum, so what is the point of the fuses? Can they be spliced out of the equation (though I would imagine keeping the fuse for the ECM might be smart?).

Can any of the relays be spliced out too? The only relays I have presently are the starter relay, ECM relay, and a mystery relay which I can't find on the wiring diagram (I think it is the fuel pump relay though).

List of connectors on the harness still:

oil pressure
throttle position
quickshifter
alarm 4 wire/kill plug
diagnostic connector for Tune ECU
MAP
Gear position
coils 1,2,3
injector 1,2,3
Fuel pump
Low fuel (needed?)
Speed sensor
crankshaft
idle speed control (needed? I have race kit manual idle adjustor)
Dash
Coolant temp
Tip over sensor (would like to keep incase of fall)
Ambient pressure (needed?, one near the intake flapper valve which isn't there)
Intake air temp
Kickstand (would like to remove but not sure how)
Clutch (need to keep for 09 bike?)
EMS main relay
Starter relay
Mystery relay (fuel pump maybe?)
Starter button/engine start stop
ECM plugs

The bike is already set up for the track with SAI remove, intake flapper, O2, and pretty much anything else that's considered not necessary for track. I have no problem cutting wires and soldering them back together. Ideally, if I could have it so the bike is "on" unless the alarm plug is removed, and cranking the bike by using an aftermarket run switch, that would be the perfect set up I think. The attached pictures are of how the harness currently is, how the alarm plug is set up, and then of the mystery relay. Thanks in advanced and sorry for the wall of text!
 

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#2 ·
You definitely want the tip-over sensor. A carbed bike will dump the fuel in the bowls and stall quickly, but an EFI bike with a reasonably full tank will keep running until the crank bearings seize.


If you're running track days and race days, you will absolutely need a working kill switch. If your right-hand switch cluster is beyond easy repair, replacements are cheap enough on eBay.


The sidestand switch is simply a matter of jumping / connecting the two wires together.


Zip-tie the alarm connector together. If it's easy enough to separate to use as a kill switch, it's easy enough to vibrate loose while running.


Edit to add: The fuses are MORE important on a race bike, since there is more available electrical power to do rude things to your wiring. The headlights and other lights are major loads consuming a large portion of the stator's output; this excess power is shunted to ground through the voltage regulator, which will run hotter than on a street bike.
 
#3 ·
I am working on the same project right now so I would love to piggy back on this thread. TTRIgnitionSystems, regarding the alarm system I have a similar question. The picture below is my currently situation, I have a working woodcraft ignition eliminator and kill switch. Is there anyway to cross the correct wires so I can cut these down to the ECU?

 
#4 ·
Not without a lot more wiring info and probably a fair bit of trial and error. The ignition / kill switch doesn't connect directly to the ECU, while I'm willing to bet that the alarm connector does. It's entirely possible that the wires for the alarm and the eliminator don't map together at all.
 
#6 ·
You can pull all of those ground wires out of that connector except for the ones that are junctioned together. The rest of those ground wires are basically dead wires.

TTRI: Good call on the fuses being more important because technically increased load. I forgot about that. I kind of figured the kickstand switch was as simple as connecting to two wires together. That definitely solves that part of the equation!

I've checked pretty much every single post regarding race harnesses in the eletrical section and I'm almost 100 percent sure that the idle speed control plug can be removed if you have the manual idle adjuster.
 
#7 ·
You don't need the idle stepper motor or its associated plug/wiring if you have the manual adjuster. Don't know whether or not it'll throw an engine code, don't know whether or not you care. I'm assuming you're trying to avoid fault codes here so you'll know if there really is a problem.

Yes, you still need the ambient pressure sensor, as well as the MAP sensor (they both look identical). I'm just going off my factory race harness here, and I still have both. I also still have a few fuses and I think 3 relays all tucked neatly away in the tail, so definitely keep those.
 
#8 ·
You don't need the idle stepper motor or its associated plug/wiring if you have the manual adjuster. Don't know whether or not it'll throw an engine code, don't know whether or not you care. I'm assuming you're trying to avoid fault codes here so you'll know if there really is a problem.

Yes, you still need the ambient pressure sensor, as well as the MAP sensor (they both look identical). I'm just going off my factory race harness here, and I still have both. I also still have a few fuses and I think 3 relays all tucked neatly away in the tail, so definitely keep those.
Sounds good thanks as always MGF. The factory race kit harness is already set up for keyless is it not?

I don't care an awful amount about error codes.
 
#10 ·
Hi there, you can get rid of the ignition barrel easily. You just need to group three sets of wires together. I can tell you what they are if you PM me. In the thread that I got the info from (it's somewhere on this site), people were concerned about laying it all out in the forum for fear of people using it for theft.

I joined the wires on the ignition barrel side of the multi connector block. You can then just remove the block plug for instant disablement of the bike. When the plug is in, the kill switch turns the ignition on and off. Easy.

Hope this is of some help? Cheers.
 
#11 ·
Awesome I'll be shooting you a PM!

This is how the bike is sitting presently. I have to make sure it can still turn on and run before I start cutting out more things :laugh:. I forgot to take a picture of it but I presently have the two wires that go to the kill switch soldered together because I had an internal break in the wires leading up to it (which took FOREVER to find). Sounds like with the way you have it set up I can remove the alarm connector plug because this will essentially be doing the same thing.
 

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#13 ·
So the race harness is coming along pretty well. Almost done. 1 question if anyone knows or not.

Is there any need to actually have the relays in there any more, or can wire them to be in the *on* position at all times. Only relays left are fuel pump, ECM, and starter relay. I am keeping the fuse box for obvious reasons, but if the relays can be switched to always on and the wires soldered together, then why not.
 
#16 ·
Oh really? That's interesting. I wouldn't have thought that. Any idea what functions it may be tinkering with the whole time? The only relays left are Fuel pump, ECM, and starter. I would imagine they stay "on" the whole time, but all 3 communicate back to the ECU, so modulation in the information relayed to it would have to do something I imagine.
 
#17 ·
That's odd that they would have one for the fan because I dont imagine any race bike having a radiator fan at this point. The 3 I'm looking at right now are EMS, starter, and fuel pump.

Starter relay is blue. Normally 5 wires though mine has 4 because I pulled the blue one that would normally be involved in the lighting circuit. Blue and yellow goes to starter fuse. Red and white goes to starter button. Brown and yellow reports back to ECU. The last red and white going to the starter solenoid.

EMS relay is black. Brown and pink going to the ECU and and ignition coils. Yellow and silver to the ECU. Black ground wire to the the bundle towards the alarm connector. Last brown and pink from fuse #6.

The last is the fuel pump relay I believe (I can't find it in the wire diagram on the service manual). It has a purple and white going to the fuel pump connector. A black and purple going to the grey ECU plug. A green and silver as wheel as a green and red, where I can't see exactly where they go because of the eletrical tape covering it right now. I think one goes to the dash connector and the other part of the starter switch/run switch complex.
 
#18 ·
I stand corrected - looking through the wiring diagram, there's nothing like a Yamaha's multifunction (relays, resistors, and diodes) relay blocks.


Never mind ...
 
#22 ·
I did similar on my SV650.


I highly recommend buying a spare harness so you can lay it out on the floor. Mark each connector function, and then start marking the wires you want to remove. (and what connector they go to!)


Rather than cutting the harness, de-pin the connector! Then if you need to, you can add the wire back in. If you can't de-pin the connector, then make sure you leave enough of a pigtail that you can solder your connection back in.
 
#23 ·
II seen your comment on a post on here about the wiring on a date and 675 I'm in the process of building a 2013 and it's almost all together and have a question for you hopefully you can still get these messages and it's not too old of a thread...or contact me 816 334 7903. Your help would be much appreciated.thanks
 
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