XJ750 dies when put “into” neutral?!

Hey there fellow XJ’ers. Ok so I have searched numerous forums and when I type in my criteria, I get plenty of “starts in neutral dies in gear” but not the other way around. My kid picked up an 82 XJ750 and I’ve been getting her fixed up. Rebuilt all 4 carbs and I’m pretty sure either the side stand switch or it’s relay if there is one, is bad. But, with the side stand down, I can clutch start the bike in gear and the wheel will actually turn. (I have it on the frame stand) but as soon as I shift into neutral, the damn thing cuts off. I’m kinda stumped as to if it’s the stand switch that would cause this or neutral safety? The warning light is flashing all the time which I would assume to be the side stand switch if anything…. Is there any way you guys know of to test these with the least amount of buy new this and that just to diagnose? I have no issue buying stuff, just would like to get it running a little first if possible lol. Thanks in advance

 

Sounds to me like the neutral switch and the sidestand switch are wired incorrectly.
The neutral switch (sky blue wire) has bullet connectors and the sidestand switch (blue/white) has connector blocks.
The wiring harness has to be butchered for them to be plugged into the wrong place.

 

Ahh yeah that’s quite possible. Although the wiring harness itself seems pretty clean as far as being torn apart and with all the other lazy shtuff I’ve seen on this bike so far, the double tape wrap seems stock. I haven’t yet found the neutral safety switch but did locate the side stand wire block. It’s I believe blu/whte grn/blu and brown wires. Thought about jumping them to rule out the side stand switch but was unsure as to which wires exactly. It was getting late last night. How can I test the neutral safety switch? And are there more than 2 tray switches on this bike?

 

Does the neutral light on the dash light up when in neutral?

 

Yes. Took me a few to figure it out since the smart guy before, reversed the linkage to where it seemed, in Normal operation, that neutral was between the last two gears lol. But yes, the light does illuminate

 

Does anyone know whether or not the 750 and 650 are wired identically?

 

Do the relays look old and original or refreshed? Wonder if someone swapped a normally closed relay for a n.o. or vice versa. The Haynes manual has relay-testing procedures (I'm not near mine right now so can't fully help).

 

Which warning on CMS?

Maxim or Seca?

Does the headlight come on with the key on - if Seca not good?

The three relays - starter cutoff, headlight (if Seca), and side stand have the same plug and care must be taken to plug them in correctly. For the side stand relay it has a blue dot and the harness was originally marked with blue tape near the connector - headlight similar but with yellow

If Seca you can swap the Headlight with Side Stand Relay and get the symptoms you describe (and more) - the Maxim does not use the headlight relay

 

They are old and I tested them out with my multimeter and they failed. I need to get a manual it seems lol

 

It’s a maxim and the headlight does come on with the key turned. The start button does work but only when in gear and the clutch pulled in. I can hear the relay for the clutch and side stand both engage properly so I’m guessing it’s more in line with a neutral safety switch problem but I can’t seem to find any documentation or picture of where exactly the darn thing is located

 

I’m guessing this is the infamous blue wire I’ve seen referred but the sleeve it’s in seems to go inside the crank case. I’m probably following wrong but it’s pretty dirty at the moment

 

That would be normal, should go out when starter button is pressed

And the side stand up?

In this thread a good pic

https://xjbikes.com/forums/threads/xj650-neutral-switch-location.75495/

 

What would keep it from starting with the stand up though. Basically if it’s in neutral, It won’t crank. If it’s in gear and stand up, it’ll crank but not start. In gear and stand down, no crank. In gear, stand down I can jump the solenoid and it will run. It’s confusing the shit outta me

 

Unless you put it in neutral and then it will die? If so this keeps pointing to the wrong relay in the side stand position or some creative wiring by the PO

So this contradicts the above where putting it in neutral causes it to die as not cranking in neutral implies the neutral switch is not working. So for this to be true you would have to have an open wire from the neutral switch to the starter cutoff relay or an open diode in the starter cutoff relay, and since it kills the bike then an improper relay in the the side stand position

So what does this mean "they failed"

You can disable the ignition cutoff for troubleshooting by either removing the side stand relay or disconnecting the B/W wire at at the bullet connector near the TCI. If the bike runs like that you can be sure you are chasing a safety circuit issue



If the diode is open in the starter cutoff relay or the wiring to it is open then the starter will not engage in neutral, but will engage with clutch pulled in AND side stand up

 

A picture is worth a thousand words, and those diagrams are priceless.

I also made this video for another thread recently, perhaps it'll help you confirm your relay thoughts, OP: https://youtube.com/shorts/ZQrVxoSt_Sw?feature=share

 

Well, now based on those very detailed diagrams, I’m guessing I have the wrong relay on the side stand. I purchased some identical relays off of Amazon to replace the old ones but I am now thinking they are relayed on the wrong pins. The neutral cranking issue is I can only jump the solenoid to get it to crank but it won’t actually start. If it’s in gear, I can use the actual start button to crank and it will only start with the stand down. It will only crank with the stand up but I literally have to drop the stand while cranking to trick it into starting. I’m going to make a video tonight and link it if that would help.

as far as the relays failing…. I just meant I had zero connectivity through any pins testing cold

 

Ok here’s a video of my issue. Could it all be from the TCI?

 

So, are the relays completely different then? Any idea where to get an aftermarket one that works for the side stand?

 

Normally, the footprint is the same on the safety relays, which is why they can inadvertently be connected to the incorrect location

Electrically, they are all different and care should be taken when searching for "aftermarket" as failure of the part can lead to a dangerous situation.

And no the automotive relay you have installed is not going to work unless it has a set of normally closed contacts