End of my rope xj700 no fire...

I know , you've heard it all before , check previous threads , etc, etc...I've done all that on my sons xj700 and cannot get fire at all. I've replaced the ignition box, tried coils, new rectifier, new harness(checked continuity), tried to find voltage values for all the sensors,coils,boxes. Just won't spark! This is year 3 after we rebuilt his bike and it ran when we bought it. He was 16 and his first vehicle. Total rebuild and nothing. Very frustrated. Just want my son to benefit from his own hard work.
I'm desperate and need help. My time is limited so I need answers for him....please someone help.....

Bob

 

I am literally in the same boat as you I have a 1982 xj550 that I have completly checked the harness, all relays, coils, fuses etc and I don't know where to turn

 

Shortly after i got this very used '85 700 maxim , it ran fine for a couple of months then one day with no warning , it just would'nt start and had no spark. At that time I had absolutly no expierince on really any bike and had not found this site till much,much later, So anyway someone gave me advice that theese bikes were known to have the pick-up coils go on them pretty often. Got one from E-bay, changed it myself and has run ever since. I am talking about the secondary pick-up under the stater cover. Dont know if you checked or not, i did'nt even know how to test the old one, just got lucky, but if you did'nt check, test or change, it might be worth a try. But to be sure, there are alot of guys on here that know more than i ever will. Good luck, I feel for you and your son's situation, Have done two total restorations with my boy now, so I know how you feel.

 

One spot that often gets overlooked in a no spark situation is the handle bar.
The control switches are grouded through housing to the handle bar.

A simple test would be to run a ground wire from the frame to the switch housing.
If you repainted the frame make sure all grounds touch bare metal.

~Ghost

 

I found this video very helpful

 

3 thoughts side stand switch, or as Mi Ghost said the handle bar kill switch. Or have you upgraded fuse block? and if so are all the wires connected as per wiring diagram? oh wait the X has fuse block under gauges correct? When I say check , I mean with an Ohm meter ,check for voltage as well as continuity ,resistance . Carefully check TCI plug for melting at plug, as well as at the coils. When you stated you replaced coils what about caps on the plugs? Check ALL the grounds for corrosion. Sorry I don't mean to get overly technical , just my aviation back ground .

 

The 700 has fuses in the cluster, but there is a fuse under the seat, too----

 

thanks for all your responses guys! I've checked all this but , am going back to recheck everything to be sure again. The video was informative in the method of testing so that made me think to recheck again. I'll keep you posted with results.
Thanks again , Bob

 

Update...found I think an issue with the side stand switch. Can't get resistance one way or another so I by passed that. Still no fire. Tested the coils , primary and secondary and they're good. Got to the little black plastic relay right beside the TCI and couldn't get a click from it no matter how I connected power across the tabs. There should be some sort of click to indicate activation right? so That's where I am so far. If you have any input , I more than welcome it.
Oh and there was a power problem with the 30A fuse under the seat so I replaced the wire and assembly with updated wire and blade fuse.

Thanks , Bob

 

Unless I am mistaken. That relay by the TCI should be the side stand relay, and it should click when the key is turned on.
~Ghost

 

From Lens Post The Ultimate Relay, Switch, Sensor, and Diode Guide:

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

XJ700 and XJ750-X models:

Flasher: combined with ignition cut-off relay.
Flasher canceller: combined with ignition cut-off relay.
Starter motor solenoid/relay: attached to and centrally behind the battery box.
Starter/Ignition cut-off relay (no color): behind gas tank on frame tube cross-brace.
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.

The side stand relay has a set of normally closed contacts. When the contacts are closed the TCI is disabled and will not fire the coils. You can simply unplug the side stand relay momentarily to rule out problems with the side stand safety circuit. Note Len's reference of the blue dot that should be on the relay in case you have accidentally installed the incorrect relay.

 

Woooooo!!! I got it!! That relay was indeed the problem! I took the one off my XJ1100 to see if they were the same (my great luck they are). Plugged it in and bingo , fire!!
I'm beyond excited for my son right now. The video posted earlier made me realize I hadn't checked the relay.
Thanks for posting all your suggestions folks. You've all been a tremendous help with my 1100 and my sons 700. Very appreciative.
Once we get it final assembled now, I'll post up some pics.
Thanks again!! Bob

 

Yaaaay!!!

 

I guess it should also be pointed out that all these items are combined into one big "black box" unit and is no longer a small "cube" type relay........only on the XJ700 and XJ750-X models.

 

Yes, my eye was on that as well. But I lucked out with finding the small plastic relay. I gave him mine from my 1100 to get him running. Thanks.

 

Well , it runs ,but! Now there's a high idle problem. Like I mean 4-5000 rpm high. Starts off normal but then suddenly revs for no reason. Flicking the throttle makes no difference. Have the carbs off now inspecting them.....any thoughts?
Bob

 

Throttle shaft seals?
Float levels wet set?
Running Sync?
Color tune?

~Ghost

 

Color tune?...

 

One of the last steps in the final tuning process. It involves using a see through spark plug to adjust the fuel mixtures to the correct burn color.

Make sure your floats are set correctly, and the carbs have a running sync done first.

~Ghost

 

Aahok. I have the carbs apart , and they're quite gunked up and corroded too. Have to do a major clean before anything else can be done.
Needless to say since the float shaft is seized , they won't float thus the high idle problem.
Thanks for all the help. This should be the last of the problems as far as I can tell. We'll do tjetuning afterwards.
Bob

 

Well , I promised a picture my sons XJ700 when it was good to go. So here it is in restored condition in a Nissan color ,deep purple. Almost looks black except when the sun hits it. So much red and purple pearl in it. Frame is black then dusted with one coat purple pearl and cleared. He's 18 now did all but the paint himself which I did. He prepped with body work though , I only sprayed color. Very proud of his hard , and good work.

Thanks again everybody. Bob

 

Wow, beautiful bike. You guys did a great job, something to remember!