1978 Yamaha XS400 full tune up

[arm]

Then the problem is in either your tci box or the pickup coil on the end of the camshaft. By switching the wires, you proved your original coil was still good and probably didn't need to be replaced.

Nah that coil pack was for sure done, had burn marks on the under side of it and was spitting out this wax like material, not sure if it was hot glue from the previous owner or some sort of insulation.

The TCI box and pickup coil, would you happen to have a picture for them and how I can begin diagnosing this further?

 

[CaptChrome]

I think you have the coils wired up wrong. that 2-prong connector is from your ignition and is supposed to connect to a coil. Based on the wire colors, that loose connector looks like it should be connected to the right-hand coil. You need to trace the wires from your ignition to the coils to make sure they are correct. Here is what the factory coils and connectors looked like.

From your ignition, you should have Red/White and Gray wires leading to the left coil and Red/White and Orange wires leading to the right coil. From your picture, the yellow wires on the coils connect to factory Orange or Gray wires and the black coil wires go to the Red/White factory wires in the harness.

 

[RadlagerMike]

this looks like from the model after 1779, he has the older one with a mix up with the coils

only the newer bikes with the cdi have this connectors, the older ones have round ones

 

[tstidham]

I was under the impression it was an 1980 or newer. I see now you have a 1978, so it should have points. Pull the points cover off the left side of the engine and inspect them. Check the points gap is correct. They can get arc carboned up if their really old so they may need to be replaced. There is also a condenser wired inline that can go bad. Sometimes you can restore functionality with some fine sand paper to clean up the contacts.

 

[CaptChrome]

only the newer bikes with the cdi have this connectors, the older ones have round ones

Ah, yes my photo is of a 1981 bike. I didn't know the pre-1980 bikes had different connectors. Also, I zoomed in on @arm's "loose" connector and it looks like an orange and gray wire installed in a newish connector.

So I was wrong on both accounts! This typically happens when I discuss anything with my wife, or so I am told....

 

[arm]

I was under the impression it was an 1980 or newer. I see now you have a 1978, so it should have points. Pull the points cover off the left side of the engine and inspect them. Check the points gap is correct. They can get arc carboned up if their really old so they may need to be replaced. There is also a condenser wired inline that can go bad. Sometimes you can restore functionality with some fine sand paper to clean up the contacts.

I think i opened up the right part of the bike, here's a video on it
Link

It looks to be clean and new, nothing wrong with any of the contacts so I'm really scratching my head as to what it could be, maybe cable is broken? maybe its something near the battery since that's where the orange cable leads to

 

[tstidham]

Ah, someone removed your points and installed the mikes xs electronic ignition kit. I also bought the same kit, but haven't installed it yet. There is a warning on the install instructions to not leave the ignition turned on for too long without running or it can be damaged. Not sure why or how that should damage anything as I'd think running would be more heat or power then just turned on. You can download the install sheet to see the wiring details, hopefully something is just wired wrong.

 

[arm]

Update on the XS, I found this amazing video for exactly the same points-based system by Brick House Builds. I been keeping up with his xs400 build and when I was debugging this issue I came across this video

In his video I noticed this

You can see the plate with the PCBs has a notch at 12 O'clock where as mine (right side) is more at 9-11 so i think that plate needs to be reinstalled because the video explained that there are magnets in the process that help control timing and spark, im not sure if this is for sure the reason why the left sidde dosent spark but im willing to give it a try.

Also his rotar has a small indicator thats at 12 O'clock aswell with the 2 silver dots facing the right. in bike i noticed that my rotars silver dots are facing downwards, Im pretty sure this isnt to alarming though since (if im not mistaken) the rotar spins and maybe mine landed at that position from the last time i rode the bike but just to be safe i think the safest thing would be to reinstall the points based kit according to the manual

I also managed to strip the screw in the top right position so any tips on how to get that out would be cool
I tried using a really long flat head but no luck, im thinking of using a even longer flat head perhaps

 

[arm]

Update:

So the previous owner routed the wires from the ignition system to some wire that then went into the coil, I thought that was weird so I unplugged them and wired the ignition straight into the coils. Still, no luck, only one spark plug is firing and the other isn't. So now I'm thinking either that little plate is off from 12 o clock and that's the issue. After that I'm pooped

I guess I would just contact mikes xs customer service for a replacement cause the unit looks to be perfectly fine but isn't really preforming as it should