No Spark

[RazeOrion]

New Owner of an old 1980 XS400.

Brought her home and I couldn't help but start troubleshooting before work. I replaced the spark plugs, gave it a kick-start but no dice.

Pulled the spark plugs and tested the spark. No spark. I'm assuming it's a either the battery, the regulator rectifier, or my stator.

I'm gonna pick up a new battery, but have no clue how to check the rectifier or the stator.

Any tips would be greatly appreciated

 

[tstidham]

The reg/rec only provide battery charging once running. I think 1980 was the start of electronic ignition and the tci box, so that is where you'll want to start your tests. There is a download available here for the Haynes manual that can help you get started, but you'll need to check the coils, ignition pickup coil and tci box and related wiring. Start with the fuses.

 

[RazeOrion]

The reg/rec only provide battery charging once running. I think 1980 was the start of electronic ignition and the tci box, so that is where you'll want to start your tests. There is a download available here for the Haynes manual that can help you get started, but you'll need to check the coils, ignition pickup coil and tci box and related wiring. Start with the fuses.

Can you clarify what a TCI Box is?

 

[tstidham]

It's the electronic ignition brain box, they're known to go bad after 40 some years, bad capacitors and such. Some have opened them up and repaired them. Do a search on here for tci and you'll find all sorts of info on them.

 

[RazeOrion]

It's the electronic ignition brain box, they're known to go bad after 40 some years, bad capacitors and such. Some have opened them up and repaired them. Do a search on here for tci and you'll find all sorts of info on them.

Thanks! I appreciate your help

 

[JPaganel]

Pulled the spark plugs and tested the spark. No spark. I'm assuming it's a either the battery, the regulator rectifier, or my stator.

Not necessarily a good assumption.

I would look at coils, wiring, and TCI first

Test power at coils. Test coils for resistance. Clean grounds. Make sure your fuses are good and the fuse box isn't broken.

Can you clarify what a TCI Box is?

TCI stands for Transistor Controlled Ignition. They are also called ignitors or ignition modules. Sometimes people call them CDI, but that's a different type of ignitor, not what the XS uses, so they are wrong about that.

They are hard to test - best you can do without special equipment is make sure the correct inputs are there.

It's the electronic ignition brain box, they're known to go bad after 40 some years, bad capacitors and such. Some have opened them up and repaired them.

I haven't had one go bad on an XS, but I have had them go bad on other bikes. I have both fixed them and bought replacements. Common failures are solder joints, output transistors, and capacitors, in that order.

There is one thing I would not recommend, and that is buying a used one. Replacing one piece fo 40 year old electronics with another piece of 40 year old electronics is a gamble.

There are companies that make new replacements. I would not go down that route before ruling out everything else - this is the most expensive of the potential fixes.

Do a search on here

That's pretty sound advice for most of this.

I will say - don't skip diagnostics before firing off the parts cannon. Outside of the coils and fuseboxes, most components on these bikes last a while. Loose connections and corrosion will mess you up, though.

 

[RazeOrion]

I got the gas tank off and testing the ignition coils.

I'm not sure which is the Primary & Secondary, but they're both testing at 3 Ohms. I know the secondary is supposed to be 8.6.

I'm including two pictures to clarify

 

[avemachina]

Primary resistance is what you've tested on both coils in your pictures (across the two connectors of each coil). Secondary resistance is from your orange connector to the spark plug cap (see picture). It's +/- 20%, so the max secondary resistance you should have is 10.32kOhms, and minimum is 6.88kOhms.

TIP! The newer spark plug wire with the suppression material (black, almost plasticky stuff) will have much higher resistance as length increases; especially compared to copper core. If your wires are super long, you'll have really high resistance, way above the max; if you're almost in the right region but a little high, try trimming a little bit off. I'm trying to get my own spark back by using very short wires while I wait on actual copper core wire to arrive in the mail.

 

[avemachina]

I think we're doing the same thing to our bikes right now! I read the rest of your post, and here's what I've got on the Rectifier:

"Disconnect the rectifier lead at the block connector. Set a
multimeter on the resistance function and connect its probes
between the red lead and one of the three white leads. Note the
reading and then reverse the meter probes. If that particular
diode is functioning correctly there should be no continuity
shown in one direction with continuity in the other. If either
condition exists in both directions then that diode is faulty.
Make the same test between the red lead and the other two
white leads. Carry out similar tests between the black lead and
the three white leads, Noting that continuity should only be
shown in one direction as described above."

 

[RazeOrion]

Primary resistance is what you've tested on both coils in your pictures (across the two connectors of each coil). Secondary resistance is from your orange connector to the spark plug cap (see picture). It's +/- 20%, so the max secondary resistance you should have is 10.32kOhms, and minimum is 6.88kOhms.

TIP! The newer spark plug wire with the suppression material (black, almost plasticky stuff) will have much higher resistance as length increases; especially compared to copper core. If your wires are super long, you'll have really high resistance, way above the max; if you're almost in the right region but a little high, try trimming a little bit off. I'm trying to get my own spark back by using very short wires while I wait on actual copper core wire to arrive in the mail.

Thanks a ton! Retested everything and the coils are testing at almost exactly 3 Ohms and 8 kOhms respectively!

Upon inspecting the spark plug cables, I noticed that they don't seem to be making contact with the ignition coil or the cap on the other side.

Thankfully, I've already ordered new spark cables due to the fact that the outside of my cables are very worn and need replacing anyway!

New cables come in on the 21st, and I'll install them as soon as I have them! I appreciate your help in testing my coils! The diagram was very helpful.

 

[RazeOrion]

I think we're doing the same thing to our bikes right now! I read the rest of your post, and here's what I've got on the Rectifier:

"Disconnect the rectifier lead at the block connector. Set a
multimeter on the resistance function and connect its probes
between the red lead and one of the three white leads. Note the
reading and then reverse the meter probes. If that particular
diode is functioning correctly there should be no continuity
shown in one direction with continuity in the other. If either
condition exists in both directions then that diode is faulty.
Make the same test between the red lead and the other two
white leads. Carry out similar tests between the black lead and
the three white leads, Noting that continuity should only be
shown in one direction as described above."

Hey, how's that for coincidence! I'll try getting a reading tomorrow before the party I'm having!

 

[JPaganel]

Upon inspecting the spark plug cables, I noticed that they don't seem to be making contact with the ignition coil or the cap on the other side.

There you go. High-tension wires do go bad, and it's a cheap fix.

 

[RazeOrion]

There you go. High-tension wires do go bad, and it's a cheap fix.

Thankfully, the parts are only 4 days away. Also charged up tue battery and got a 12v reading after, so I'm c9nfident I've at least got the "No spark" issue fixed on the plug-side