85 XJ700 Won't Start (No Spark)

I have a 1985 XJ700. When I got it, it worked great. I was riding it back and forth to work with no problem. One day after I got home from work (riding the bike) I went to run an errand on the bike but it would not start. I thought this was odd since I had just been riding it a couple hours before. After some investigation I realized that I was not getting spark on any of my cylinders. After a little more troubleshooting I noticed that I am getting a consistent 9.99 volts from my TCI (Red/white and black wires) with a fully charged battery before I hit the starter, and around 10.25 volts after I hit the starter. After reading some other forums this seems to be marginally enough (most say you should have at least 10 volts). It was suggested that I check my fuse box (behind the neutral light), kill switch, and ignition switch. I was able to temporarily bypass the ignition switch using jumpers to rule out the possibility of it being bad. The problem persisted. My kill switch has less than an ohm of resistance. The fuse box though old and cracked seems to be pretty corrosion free. Does anyone have any input on other things I should look at or ways to investigate what I already looked at further? Any advice is welcome. I am anxious to get this thing back on the road!

 

Hi claycing. Couple of quick questions that may help....

Does connecting another battery, via jump start, help? You also mentioned the fuse block is cracked, how badly and are you certain they are not contributing to the issue?

 

Not that familiar with the 700 wiring but I'd suspect it's a safety or a fuse. Check across all of the fuses for voltage. The side stand relay often cause issues like this, either flakey coil/contacts or the switch itself going to the relay.

 

Its a brand new battery and even with the jumper cables connected it has the same problem. i don't believe so the cracks are mostly in the block itself not near the fuses.

 

It is cranking wouldn't the side stand switch keep it from cranking? I really don't know that's just how I understood the system I could be completely wrong though.

 

Usually it won't crank but again I'm not 100% familiar with the 700 wiring. I just remember the TCI being tied to neutral and side-stand interlock so suggested looking there.

 

Ok thanks! Ill add that to my list of things to check

 

The sidestand switch is not needed for the bike to crank while in neutral or to enable the ignition cutoff as the neutral switch will do both. However, you could have an issue with the ignition cutoff safety circuit caused by the sidestand relay, or the associated wiring. You can test the sidestand switch by placing the bike in gear and pulling the clutch in, if the bike cranks the sidestand and clutch switch are working. You can temporarily disable the ignition cutoff by disconnecting the sidestand relay, which is located under the left side cover and marked with a blue dot.

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

"XJ700 and XJ750-X models:

Flasher: combined into the consolidated relay assembly unit.
Flasher canceller: combined into the consolidated relay assembly unit.
Starter/Ignition cut-off relay: combined into the consolidated relay assembly unit.
Consolidated relay assembly: behind the gas tank on the frame tube cross-brace.
Starter motor solenoid/relay: attached to and centrally behind the battery box.
Sidestand (kickstand) relay (blue): under left side cover, above regulator.
Headlight relay (yellow): not used.
Main fuseholder: behind frame crossbar, behind the battery.
Diode block: under left side cover, above regulator.
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"."
Thermo unit: screws into the thermostat housing.
Thermoswitch: screws into the thermostat housing.

 

I am having the no spark on any plugs problem. I feel like i have pulled appart and cleaned just about every connecter. I am only getting 10.5 volts from the red/white and black wires on the tci. Any other ideas?

 

I haven’t seen where you’ve done a voltage test on the battery, and a voltage drop test when hitting the starter. I know you said it’s a fully charged battery. But that doesn’t mean the battery is any good. I’ve seen numerous brand new batteries that were no good. Long and short of it is that I’d go to the battery first.

 

+1 ^^ You beat me to it

I don't see any coil testing numbers? Have not cut off the end of the plug wires a little yet? I would start with the simple things and if that all fails then you can start to check and or open up the TCI to check it.

 

What is the second thing about the plug wires?

 

I'm pretty sure it's fine but i will check again. I have also been doing a lot of these tests with a jump pack to hopefully rule out a weak battery, would that make any difference?

 

Umm, yeah!

 

Unscrew the plug caps from the wire, snip a bit off to get a better connection. Over time the pointy end of the plug boot will wear away the shield and graphite core causing intermittent spark issues.

 

ok so I've been doing that haha

 

ok I'll give that a shot. My only thing though is I'm not getting spark on ANY plugs, and it happened suddenly. Would the plug wires all go out at once to cause a problem like that?

 

Probably not, but you never know. Regardless, weak spark is already an issue on the XJ systems and a bad boot connection makes it worse. The coils checked ok? Check the resistance on both the primary and secondary windings.

 

I wonder if the brushes in the alternator are bad or got contaminated with oil. Mine did, and I had starting problems. Replaced them and all is well. Perhaps one of the online gurus will know how to test them without having to remove them. If one of the brushes broke or got stuck that could account for the sudden disappearance of a spark--or at least I think it could.

 

ok this is the first bike ive worked on so ill have to do some research on how to do that

 

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

Search for "Ignition Coils" or read through and see the abundance of information Chacal has provided.

 

Ok, I was still half asleep..... I was reading that as “to diagnose a weak battery” in my foggy brain. Ignore my response.

so, have you checked your fuses?

 

Airhead?

A good place to start:

https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

From above thread:

"XJ700 air-cooled models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range

Ignition Coils:

Primary side (input from main wiring harness):
2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range

Spark plug caps:
1985 N/NC models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
1986 S/SC models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
1985 N/NC models: 0 ohms per plug
1986 S/SC models: 5K ohms per plug"

Pick-up coils and ignition coil primaries can be checked from the TCI main harness mating connector
Ignition coil secondary check from 1 to 4 and 2 to 3 spark plug caps - be sure to total the resistance of the cap and ignition coil secondary and set the meter to the appropriate scale - 200K should be fine.

Did you ever pull the side stand relay to eliminate an issue with the ignition cutoff safety?

 

If you just lost spark all the sudden you either blew a fuse or a connector/wire is now open/shorted. Start with fusees and then the other wires and connectors. If both coils went out at same time I would guess it is a common fault and a simple one.

 

yeah i lost all spark all at once. fuses are fine. i have a potential lead on it being the side stand relay. ill let you know how it turns out.

 

Disconnect it and use a short ( couple inches long is enough) copper wire and temporarily jump it.

Don’t leave it like that...it is a dangerous practice. If you forget to raise the stand you could be tossed off on a left hand turn. A bike shop owner was killed up here several years back for that reason.

I have had to disconnect some also. When I did that, I made sure to use a kickstand plate. That way I had to manually pick up the plate, so I made sure that I manually raised the stand first. Then pick up the plate put it in my pocket. I only forgot a couple times. You won’t forget very often..... the little unexpected sideways hop will scare you into remembering quick.

 

Yeah for sure if that turns out to be the problem i'll fix it before riding

 

Don't want to confuse him - removing the side stand relay will disable the ignition cutoff - no jumper required.

You can also disconnect the B/W wire at the TCI to disable ignition cutoff. It's not normally required as the wire would have to short to ground to cause ignition cutoff, but it is a possibility that the wire is chafed shorting to ground.

 

But if the relay or the cutoff is bad, then you still won’t know. Disconnecting JUST the switch removes only ONE variable.

 

yeah i plan on shorting out the relay temporally and testing to see if that fixes the problem

 

I would not try to short anything out

 

by short i mean jump

 

This seems to be getting difficult to communicate but I will try once more.

To disable the ignition cutoff to determine if that is causing loss of spark it is only necessary to remove / unplug the side stand relay. No jumper, no shorts are required. The normally closed contacts in the side stand relay open when the ignition cutoff safety is working correctly, therefore just unplugging the relay is all that is necessary to troubleshoot that particular circuit.

 

Ok sorry i think i missed your first message and was misreading the wiring schematic I'm away this weekend so i will unfortunately have to wait till Monday to test this out