Humidity problems.

Are all four plug wires failing to have spark when the failure occurs?

 

Yes, all four wires loose spark when this occurs. But it is random when it happens. I'm starting to think humidity has nothing to do with it, but rather it was just happening during times of high humidity.

 

Agreed. What this means it that you can concentrate on everthing from the primary feeds to the colls, back.
I would verify that the sidestand switch is working both mechanically and electrically, and do the same for the clutch switch. The sidestand switches tend to get crap in them (making the plunger sticky) and will cut power to the ignition if you go over a sufficient bump.
If you still have the original fusebox you should inspect it very carefully for cracked fuse clips.
The TCI should be the last suspect.

 

I have replaced the fuse box with the block fuxes. I will check all these problem areas and post an update with what's find.

 

Start what k-moe stated by checking your connections to and through the fuse box.

Gary H.

 

Update: sorry it took so long. I have done a lot of messing around and troubleshooting as instructed. I have come to a possible conclusion that the relay 12R under the gas tank is causing the spark to kill. I replaced it with the relay 4U8-00 on the side of the bike and it ran without problems. So I went and picked up another 12R relay and started it and it still killed even with the new 12R relay. So the relay 4U8-00 will provide spark every time I crank and run it but the 12R will kill the bike after about 2 minutes. I've never had this happen in the first 2 years of owning the bike. I have never replaced any relays till now, Is this relay not the correct relay. According to the relay master guide here on xjbikes it's the ignition cutoff relay. Which kinda makes sense with something killing the spark.

 

Relay Assy (12R-01) 12R-81950-01-00


Relay Assy (4U8-02) 4U8-81950-02-00

relays listed for your bike two different relays
this link helps with relays
The Ultimate Relay, Switch, Sensor, and Diodes Guide
1982-84 XJ750 Maxim and Midnight Maxim models:

Starter/Ignition cut-off relay (no color): behind self-canceller, under rear of tank.

Sidestand (kickstand) relay (blue): behind the left frame side cover, on the plastic regulator-rectifier mounting plate

What do you replace the relay with that you remove from side of bike the 4U8 relay. if nothing this is probaly your problem


BY-PASSING SWITCHES AND RELAYS:
Starting/Ignition Cut-Off/Neutral Safety relay:
- unplug the safety relay which disables the whole bloody mess but DO NOT leave it that way, fix it right!

Sidestand (kickstand) relay:
- unplug the safety relay which disables the whole bloody mess but DO NOT leave it that way, fix it right!

basicly when you unplug the relay you bypass it putting the wrong relay in the position is the same as bypassing it.

PUT your relays back where they belong then remove the Starter/Ignition cut-off relay the 12R relay
and ride your bike to see if the problem goes away.

then repete process for the 4U8 relay

then remove both relays
you could have 1 bad relay or 2 bad relays

 

Replacing the starter cutoff relay (12R) with a side stand relay (4U8) will effectively disable the starter safety circuit. The relays have identical connectors, but are different internally and should not be swapped. Most of the relays are identified with a colored dot and a corresponding colored wrap of vinyl tape on the harness to ensure correct fitment. The starter cutoff relay is the exception to no color marking.

From Len's guide:

http://www.xjbikes.com/forums/threads/the-ultimate-relay-switch-sensor-and-diodes-guide.27543/

1982-84 XJ750 Maxim and Midnight Maxim models:

Flasher: near the steering headpipe, on right side frame rail, under the right side ignition coil.
Flasher canceller: under the rear of gas tank.
Starter motor solenoid/relay: attached to and behind the battery box.
Starter/Ignition cut-off relay (no color): behind self-canceller, under rear of tank.
Sidestand (kickstand) relay (blue): behind the left frame side cover, on the plastic regulator-rectifier mounting plate.
Headlight relay (yellow): not used.
1982 XJ750 Maxim safety relay single diode: outside the main wiring harness bundle, in the area just behind the fuel tank.
1983-4 XJ750 Maxim Diode block: inside the headlight housing.
Neutral switch: in a hole in the bottom of the crankcase, just "outside" of the oil pan, on the bottom of the engine, up inside a recessed "well".

When you replaced the starter cutoff relay (12R) with the side stand relay (4U8), and if you did not install a relay in the side stand relay position, then you disabled the side stand safety circuit and the TCI was always enabled. Therefore, if this was the case you have isolated the problem to the side stand safety circuit, which is made up of the side stand relay, side stand switch, neutral switch, diode block, and associated wiring.

When riding in gear, the side stand switch is totally responsible for engaging the side stand relay and opening a set of normally closed contacts to enable the TCI. The neutral switch is wired in parallel with the side stand switch through the diode block, so if the bike died in gear, but would restart in neutral, then that would point to the side stand switch. If the bike will not run in either instance, then the side stand relay or wiring becomes suspect.

So, in summary from some of the earlier post to isolate the problem:

Temporarily remove the side stand relay to disable the side stand safety circuit, does this fix the problem?

The clutch switch will not cause a shutdown of the TCI, it is used in conjunction with the side stand switch to start the bike in gear. If you have a working clutch switch, then you can use this as a troubleshooting aid. When the bike dies, can you engage the starter with the bike in gear and the side stand up, if so the side stand switch is working and is not the root cause of loss of spark.

The starter cutoff relay will not cause a shutdown of the TCI. It does exactly as the name applies, and shuts down the starter if the correct parameters are not met to safely engage the starter. Removing the starter cutoff relay will not bypass the circuit, but instead will just disable it unless a jumper is installed from R/W to R/W. You don't need to go there unless you are having issues with engaging the starter.

 

If the plug wires are cracked do you have to change the coil?

 

no you can splice in a new wire NGK makes a nice splice you cut existing wire back leaving some of the old wire and do the splice.


NGK--8083 Local auto parts store or link below
http://www.edgextremesports.com/store/NGK-Cable-Splice-8083.html?gclid=CJGBotzguMsCFdgegQod1zMHmg

or you can did out the old wire and reglue in a new wire . there is a thread on this someplace

 

http://www.xjbikes.com/forums/posts/257495/

 

If you splice, wrap self-amalgamizing tape around the remainder of the old wires to insulate it.

 

Thanks XJ, I ordered a set today!

 

I took the 4u8 relay out and am able to ride it with no problems. So this relay is probably causing the problem. I will replace it and see if the problemreturns.

 

it is the sidestand safety switch relay could be your sidestand switch is failing check it out

 

+1 Because of their location, the sidestand switches are prone to get grimy and sticky. Corrosion can also be a problem. I clean mine annually and use a dry-film lubricant.

 

Update: I think I bypassed the kickstand/neutral relay, my rubber cover was ripped and it looked like it was a 2 piece plunger style relay. I just left the relay part and took the second plunger out, that the kickstand hits, completely. I also tightened up my clutch cable because it was a bit loose. I noticed it seemed to get up and move better after that. I let it warm up for about 30 minutes and took it around the block about 12 times and it didn't seem to have problems with loosing spark again. but that don't mean the problem is fixed. I'll have to ride it a few more times before I can be sure.

 

You basically did disable the sidestand switch. If you don't have a repeat incident then you can pretty well assume that the switch needs at least cleaned out, or replaced. A better way to bypass it is to just unplug the switch. The way you have it now does leave the possability that it can trip the switch with a bump if there is enough corrosion in the switch.

Clean them is pretty easy, but does nto always work. Since the switch is cased in epoxy the only real cleaning you can do is to spray contact cleaner up into the plunger hole and move it around to loosen things up. The contact cleaner will spill back out when you tip the switch housing.

 

[QUOTE="A better way to bypass it is to just unplug the switch.[/QUOTE]

I did try this. But for some reason the bike wouldn't start all together in neutral or in gear.........least I believe I followed the switch up to the TCI biggest plug with two wires coming out to a ground and power I'm imagining?

 

I did try this. But for some reason the bike wouldn't start all together in neutral or in gear.........least I believe I followed the switch up to the TCI biggest plug with two wires coming out to a ground and power I'm imagining?