Yamaha XS400 Wiring Diagrams

if you can use a kick-start the simplest to get the bike running for test purposes is

live feed to both coils from battery

earth feeds to coils provided through the contact breakers with condensors off that to earth

that's it, don't leave the coils live for too long or they will heat up and break.
Srry the other post was confusing, exactly what wires do I need power to and to ground to do this
 
Jason, I think this fits your bike...

make sure your coils and ignitor unit are hooked up correctly, then simply hook up the red and white wire (R/W in diagram) to a 12v battery somewhere in the middle.
If that is attached to your solenoid as in this scheme, it should start immediately. If not, your harness may be different...
anyhow, get power to those coils, and use a jumpercabel to bypass the solenoid if neccesary to test it;
+ goes from your battery to the cable on your solenoid
- goes directly to mass on your frame

I myself built this test wiring form scratch... I can be of no help if you're trying to do this via a complicated harnass :shrug:
 

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So the wiring coming out of the head and the coil need power and ground to start for some reason I just can't picture what to connect lol I just wanna make shire the engines good
 
To get your engine running, all you need is the top bit of the diagram.
First, check if your bike has the old contactbreakers, in which case you need to add a condenser, or pickup coils and a regulator as in the scheme. Your coils each have two wires and the sparkplug cable. Get 12 volts to the wires that have the same colour (red/white). Now, with old style contactbreakers it's easy: figure out which wire coming from the engine fires which cilinder (orange - right, grey - left... Or the other way around... Easy stuff). These you can then hook up to the remaining wires on the coils. BUT, in between you need that condenser. The original part seems to be two condensers, attached bottom to bottom... It doesnt matter which side is hooked up to which coil, its just one wire per coil to engine connection.
Once you have this in place, hook up the battery, get your fuel flowing and start kicking/power up the starter

Cheers
 
I have what I believe to be a 1980 3F (at least that's what the vin says) I was wondering why my pickup coloring was different than everything else I have seen. I have a black, a white and an orange. Trying to figure out how this mates up. The 81 diagram shows a red, blue and black. Any ideas would be helpful.
 
I found this thread over the weekend and it really helped me out with the rewiring of my 400. I stripped everything and used all new 16g marine wire, as well as a Rick's Motorsports regulator/rectifier. This schematic is confirmed to get my bike running, and the battery charging at a steady 14.5v max (when revving).

I'm running an LED headlight, and a brake light - no dummy lights. Using a small 4aH sealed lead acid battery. Figured this could help some of you running a similar setup.

xs400-wiring-harness-new.jpg
 
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82' xs400 maxim
0614161655.jpg
I read this whole thread and I have not found or seen this relay anywhere. I purchased the manual and it does not show in any of the wiring diagrams. Any one knows what it does or is for??
 
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82' xs400 maxim
View attachment 26976 I read this whole thread and I have not found or seen this relay anywhere. I purchased the manual and it does not show in any of the wiring diagrams. Any one knows what it does or is for??
I'm not too familiar with the DOHC bikes but nobody else is chiming in.
As near as I can tell it's probably the clutch safety relay, but the colours don't quite match what the manual says they should be. Should be able to follow one of the wires back to the clutch switch on the handlebars.
Has anyone? Im in that same pickle...need to know which wire goes where...
With that exact relay? Your bike isn't a DOHC so you'll have two similar looking relays. One is the clutch safety relay and one is the headlight relay. The colours in the wiring diagram should match up pretty well to your bike, which will identify which relay you're looking at and what it does.
 
I'm not too familiar with the DOHC bikes but nobody else is chiming in.
As near as I can tell it's probably the clutch safety relay, but the colours don't quite match what the manual says they should be. Should be able to follow one of the wires back to the clutch switch on the handlebars.
With that exact relay? Your bike isn't a DOHC so you'll have two similar looking relays. One is the clutch safety relay and one is the headlight relay. The colours in the wiring diagram should match up pretty well to your bike, which will identify which relay you're looking at and what it does.
Got'er thanks though!
 
Sorry to beat a dead horse and i am new. I picked up an old 81 XS for FREE. I just want the bike to run. I have went thru every page of this thread and i cannot find a diagram for the absolute minimum. I also want to use a dirt bike kill switch as a start button as well as another one for the kill switch. Again NO LIGHTS, NO SAFTEY SWITCHES. BUT electric start. HELP Sorry again if this isnt right. I am new to this forum Thanks again.
 
You know what ends up happening, is that some people will post in to the bigger threads. so you will find some of the diagrams in the middle of the "What I did today to my XS400" thread. If you have checked out the Tech section, Drewpies re-wire is nice because you look at it as a big picture, and then you can strip out on the outset of what you don't want to support. So it ends up being you and your buddy Google to find the one your looking for. Others will do like you did, and put it into a "current point" of that thread, totally unmarked as a diagram. Since 2010 when this went on line for me. I have seen many, and like the first one I clicked on to see if I can help you with a quick google search, I ran into a thread marked, "now I can not shut it off" You know what that means, That guy found one. chances are if you went though all of his posts, he will tell you where he found the minimum wire diagram that he used, before he found out there was no kill switch. Alot of the builds have the same thought, after they started the build, and want to update to LED's, or more brilliant headlights. Sorry for not being super helpful. but here is that thread I found.
http://www.xs400.com/threads/engine-wont-shut-off-with-ignition-turned-off.10786/#post-112586
 
Where can i find an ignition switch like this? I guess the original key switch is getting me held up when using this diagram
 

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There's not a lot of specific material for the Maxims. There is a Seca manual in the manuals thread at the top of the Garage.
It has a wiring diagram and I'm fairly certain the electrical is identical between the models.
 
Hi everyone. I have a 78' xs400 and im starting to work on it on my own. The taillight of the bike is on while im riding and idle but it does not respond when I break. There is no intensity in brightness of tail light. Any suggestions as to what to look into for this issue?
 
Hi everyone. I have a 78' xs400 and im starting to work on it on my own. The taillight of the bike is on while im riding and idle but it does not respond when I break. There is no intensity in brightness of tail light. Any suggestions as to what to look into for this issue?


Welcome and is the rear break light switch hooked up? Also there should be a switch on the front break on the handle. They both can be adjusted.

78 you have discs front and rear ?
 
Foot pedal sensor is on the frame, near the behind the foot pedal. (at end of the solid wire) adj by big plastic nut. (at least on the 81.)
 
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I found this thread over the weekend and it really helped me out with the rewiring of my 400. I stripped everything and used all new 16g marine wire, as well as a Rick's Motorsports regulator/rectifier. This schematic is confirmed to get my bike running, and the battery charging at a steady 14.5v max (when revving).

I'm running an LED headlight, and a brake light - no dummy lights. Using a small 4aH sealed lead acid battery. Figured this could help some of you running a similar setup.

xs400-wiring-harness-new.jpg
Thanks for this rafanomenon. I was apprehensive to use this, but it’s the only diagram I could find that shows the pickup wire colors. I’m new here, but I know I’ll be back. I’m building a “ground up” bike using an XS360 frame (among other things) with an XS400 motor. Since I don’t have the wiring from the XS400 (1981 XS400S) I was thrown for a loop on connecting the pickup to the igniter unit. There’s no correlation between the pickup wires and the ignitor wires. This is the only diagram out there that shows how to make the connections. Appreciate you confirming the accuracy of the diagram.
 
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