No Spark! (xj750rh)

I have no spark from any leads. I have tried a spare ignition control box and checked out all relays. The only thing I can think of checking out tomorrow is the pickup coils. Any suggestions?

 

See my post on using Honda CB 750 from 80 to 83...you can find them on ebay cheap..these have replacable plug wires and mount same as stock. Carefully look at your coils to see if they are cracked, also unthread the plug cap cut off a little of the plug wire and thead cap back in. I swapped to these Honda coil as I had them for years from a CB 750 I had sold (MISTAKE 4500 MILE MINT) and my coils on my 82 XJ750 Seca were cracked but still working. My bike runs very strong and have had no ignition problems.

 

The problem ended up being the top pickup coil. It was an open circuit. I had a spare. All is good now

 

I am having a similar problem. I found a shorted switch on the bars and fixed it only to fry the wires, sizzling and smoking from where the fuses should be. The fellow previous did some suspect things to the harness. With the help of the son in law we rebuilt the harness. Two questions: Can the side stand module be wired out of the ignition circuit and bypassed and how likely is it I have fried a pick up coil or blown the computer. We are putting the harness on on Sunday and I am mentally preparing for failure. This project has been an electrical nightmare. Might as well be a Triumph!

 

take out the sidestand relay to bypass the sidestand switch.
you can ohm out the pickup coils at the tci connector . gray to black and orange to black. ohm out the full ignition system.
you can find info on relays and ignition specs in this thread
The Ultimate Relay, Switch, Sensor, and Diodes Guide

it would be best if you started a thread of your own to allow us to help you better. what bike do you have?

there is a minimum wiring diagram on this site if you wantto go minimum or atleast wire bike to get it started

 

1981xj750RH. Checked the pickup coils. They are good. When the sidestand relay is out I get nothing, no solenoid click, no turning over. The actual sidestand switch tested fine. It's all together now but when I hit the start button all I get is the clicking solenoid. The starter bench tested fine. Solenoid bench tested fine. Battery at full voltage. I have cleaned the ground, still just a click. I might wave a dead chicken and dance naked soon as nothing else is working.

 

And thanks for the reply and the links

 

If you bridge the solenoid and the starter cranks, then it's a bad solenoid. If it doesn't crank, it's probably a bad starter (brushes, maybe).

Also, since you had the starter out to bench test it, are you sure it's wired correctly after reinstall?

 

+1 on checking starter / solenoid by bridging the two large nut on the solenoid. It would be difficult to bench test a solenoid to be sure it could supply the necessary current for the starter

That should not happen unless you are trying to start it out of neutral. The side stand relay should be marked with a blue dot and the corresponding plug should have blue vinyl tape to identify the correct wiring for the relay. Sounds like you are pulling the starter cutoff relay?

Location of relay per Lens's write-up:

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

1981-83 XJ750 Seca and XJ750 Euro 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 battery box.
Starter/Ignition cut-off relay (no color): behind coils, behind self-canceller.
Sidestand (kickstand) relay (blue): frame bracket outbound of LH frame tube, just behind the left side ignition coil.
Headlight relay (yellow): behind the left frame side cover, on the plastic regulator-rectifier mounting plate.
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".

 

Thanks very much for the replies. They have been helpful. In the end I had a grounded starter switch, bad sidestand module and a bad bad main ground wire; the connections looked great but the wire was badly corroded inside. I still have to finish the wiring, signals, lights etc but she is screaming, not a miss. Woot. My first ride in twenty years will be up my 13% grade rough gravel drive, complete with hairpin. Once again. thanks to everyone who took the time to post. Cheers.

 

Gravel drive/hairpin, flat out in third then, yes!!!