XJ700 wiring

OK , my son has an '85 xj700 air cooled. We've disassembled his bike for a complete repaint of everything. When he put everything back together it does not have any power at all. I've checked his groung points andthey look OK , but , there was a ground wire that came off the harness that he doesn't know where it came from. The battery ground has a wire coming from it that we can't find a connection for. Can anyone tell me all the proper ground points for this bike? It was running when first disassembled , but he had just bought the bike.
We have a manual but it's not helping with where gnd points are.
Thanks

 

Best photo I could find on another members XJ700. The negative side of the battery has only one wire, the very large wire that should bolt to the engine. The smaller wire you see is a battery tender hookup.

The positive side has two, one going to the solenoid and on one going to the a connector that routes to the main fuse.

Can you post a pic of that wire? Some of the XJ's do use and extra ground wire to bolt from the engine to the frame, not sure about the 700.

 

That's a big help. I'll post a pic when I get a chance. I don't recall right now a second wire from the batt to the connector to the main fuse. Thank you! I'll keep y'all posted

 

Awesome! That was it. He mistakenly soldered the wrong wires together so that there was no specific one to the batt besides the start solenoid power. Once we have it back together we'll post pics of our bikes. Also found that extra grnd too.

 

OK , what are the chances that my son with his xj700 would have the same issue as my xj1100....have power , it cranks forever (after a starter clean up) but now there is no spark at all! Is the wiring that bad in these things? I have a new TCI coming for my 1100 to solve my *fire in only two cylinder problem* and now I cant get fire in his xj700. He's away working for the summer and I'd like to have this thing running for when he gets back in a couple weeks.
I've checked for ohm readings in both pick up coils and ignition coils and they read fine all the way to the plugs at the TCI. So does this mean the TCI is gone?
Need help! I'm at the end of my rope here!

 

First be sure you are correctly checking for spark as required per the wasted spark system. Check one plug at a time with the other plugs connected and grounded.

The TCI can be disabled by the safety circuit. Normally, with the bike in neutral or the side stand up the side stand relay is energized, which opens a set of normally closed contacts within the side stand relay to enable the TCI.

Make sure the correct relay is present for the side stand relay (blue dot) and that the correct part of the harness is connected to it (marked with blue vinyl tape). You can also try unplugging the side stand relay temporarily, and this will bypass that portion of the safety circuit and allow the TCI to always be enabled.

 

I've gone over all this but I'll double check. Maybe there's a switch sticking. Thanks

 

It's not that the wiring is, or was ever bad on the XJ series; it's the fact that they are over 30 years old. Everything that old needs attention. In perspective, we are the analogue to the old guys of our youth who were still riding flathead Indians (that could be bought for cheap) even though they could afford a brand new CB750.

 

Well I've gone over all the switches and still no fire. Pretty frustrated right now.

 

Describe gone over. Which switches? Have you cleaned the sidestand switch, or tried bypassing it, or removing the sidestand relay?

 

The switches related to starting . cleaned and tried bypassing the side stand relay. Its a new clutch switch. Checked to see if power is getting to all components and there is. I just don't understand how this can just not fire when everything seems to be okay. Maybe the igniter box is fried. I just don't know.

 

Maybe this will help...
http://xjbikes.com/forums/threads/how-to-test-your-starter-circuit.7828/#post-64876

 

My problem isn't that it won't crank. It cranks for days. The problem is no fire. Doesn't make sense that everything works except spark. I appreciate your digging for me though. Something's gotta give here soon, jeeez

 

Some thoughts:

Verify battery voltage during cranking. If the voltage drops too low the TCI will not function correctly. A good battery will maintain a voltage of around 11 volts with the starter spinning. Anything below 9.5 volts will cause an issue with the TCI.

You had a running bike before disassembly to paint, so not likely the TCI is bad. Did you check the pick-up coils to ground when testing them at the TCI connector? Make sure none of pick-up coil wires go to chassis as well as verifying the correct resistance for each pick-up.

Did you check the secondary resistance on the coils, plug cap to plug cap? I believe the correct reading for your bike is approximately 32K, 12K for the secondary with 2X 10K caps. Check 1 to 4 and 2 to 3.

Find the B/W wire on the main harness mating connector that connects to the TCI. On the earlier models there was a bullet connector on this line that could be disconnected. If it has the bullet connector, disconnect it as this is the absolute best way to rule out an issue with the side stand safety circuit.

Check the voltage to the TCI, R/W wire to Black wire, should be about 11.5 volts with the key set to on and the kill switch set to run.

Check the voltage on the ignition coil drive lines at the TCI. If the power was OK in the above step you can use chassis ground for the negative lead. Voltage on the Orange and Grey wire should be around 11.5 volts. One may be low momentarily when power is first applied, which would be a good sign for the TCI working.

 

I will check these steps and keep you posted, thanks guys!

 

Man I just don't get it. I'm not getting any kind of secondary resistance from either coil. There is a correct resistance reading at the plug though. How can this be? We're getting good power readings as well all across the board as you suggested we check. Does this make both coils bad?

 

What does this mean? Are you getting good readings from plug cap to plug cap for each coil, and bad readings with them off?

If the reading are good at the plug caps, then time to looks somewhere else for what is causing no spark.

If the readings are bad with the plug caps on, then the caps need to be removed and the coils and caps tested individually to isolate the problem. If the coils and caps both check OK, then trimming a quarter inch of wire from the plug wires and screwing the caps back on should solve the problem.

 

No , the readings are good where the coils plug in the harness. Plug cap to plug cap is nothing. We'll measure one more time as we anip off a bit and see what happens.

 

So it turns out that without plug caps on I get no reading with both coils! One plug cap reads over 10 ohms and one is nothing at all , the other two both read 4.75. And the caps are measured individually.

 

And for sure the meter is set correctly, not sure what meter you have but most members have selectable scale ohm meters so be sure the meter is set to a reading higher than the expected reading. In this case, the 12Kohm coils the meter should be set to a setting of 20Kohms. If the coil was exactly in spec, it would result in a display reading of 12.00, which would be 12Kohms. If you use too low a scale, say like 2Kohm, the meter will display "1" indicating an overload condition.

So, if your meter is set correctly, and you are indeed touching bare wire within the plug wire and checking 1 to 4 or 2 to 3 then it would appear that both coils have a defective secondary.

As for the caps, I had stated earlier they were 10Kohms based on the FSM. Per Len's catalog the air cooled 700's are supposed to be 5Kohms. I would tend to trust Len's catalog more as the FSM's are known to have mistakes. Also, depending on the version of the cap, some can be cleaned / rebuilt. If you look up inside the spark plug cap where the spark plug goes and see a slot then it can be disassembled, inspected, and perhaps just cleaned up to put back into service.


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

 

It's as you stayed most use the selectable meter. That's what I use and it was set to 20Kohms. His bike is the air cooled version. So I guess we look for coil's now. Thanks do much for the help. I never would have been able to track this problem down with out the knowledge here on XJ bikes. You guys are great!

 

So can you tell me what would be happening if the coil measured good at the harness plug , measured good for secondary without caps on , caps measured OK , but with the caps on the wires you couldn't get a reading? I ask because I think this may be happening to my XJ1100.

 

First thought is the meter is set to 20Kohm range, 11K coil OK, 5Kohm cap OK, but 11Kohm coil + (2 x 5Kohm cap) = 21Kohm, which would put the meter out of range.

Other than that, if each individual component measures OK, then there has to be a contact problem when assembling, or the assembly causes an open to occur either in the wiring or one of the caps. If the meter is set correctly, then try installing one cap at a time to isolate the problem.

Here is a spark plug cap that can be cleaned / rebuilt, note the slotted end that can be unscrewed. Sometimes they just work loose a bit from installing on and off the spark plugs.

 

I was reading this topic because I recently encountered the same problem as well. Hopefully this is not a thread jack.

I measured the primaries and they are perfectly within spec. The bike was running at the beginning of the summer when I parked it to work on it (backwards...I know...you're supposed to ride all summer). Caveat: I had an ignition problem, but I think I fixed it when I cut and reattached spark plug end #4, which was badly corroded between the wire and the cap.

So, I know the bike runs as it is, which is not to say that the secondaries are fine. But they were working...and I can't get any resistance measurements on the secondaries, either by the method shown in the manual (on the harness and the high voltage wire), or by going between #1 and #4 plugs or #2 and #3 plugs. It just seems unlikely to me that not only would both secondary coils be bad at the same time (although this obviously could happen), but that the bike would also run in that condition. Are we all missing something here? I seem to have the same phenomenon going on...

 

you need to trim back your spark plug wires

 

wrong meter setting? the spark plug wires are the secondary, where do they hook into the harness?

 

Yep, you are 100% correct---turns out that I should have paid no attention to the fact that it was running. All my caps/wires were in bad shape. Thanks for the help!

Unfortunately, I get no reading on the secondaries, even with the caps off and the wires trimmed back. I guess I need new coils...boo. I suppose the other posters probably have the same things going on...

 

running but no reading on plug wires? turn your meter up a setting.
you are testing 1 and 4 as a set and 2 and 3 as a set?

 

Moved it here:

http://www.xjbikes.com/forums/threads/coil-problems.71995/