JDX8 Lost All Spark

[kiedro44]

I'm hoping this will be a quick post and an easy solution. Was having weak/no fire spark issue on one cylinder on my '73 KEC 440/21. Had it running but flywheel side was not igniting. So with motor out of the sled, I took off the flywheel, took out the stator assembly to inspect. Looked good. Put it back together but then I had no spark at all. Did it again and replaced the condensers as this was my plan anyway. Still no spark. What did I mess up? Motor is plugged in to wire harness sitting on motor mounts, and external coils are plugged in, and key is "on" but both plugs are dormant. Is there a trick to re-assembly of the flywheel or something else like a ground wire I'm missing? Any thoughts?

[JD600]

Try unplugging the engine from the machine harness. You should have spark with the engine unplugged. If you DO have spark with the engine unplugged, you more than likely have a bad key switch, or a bad kill switch on the throttle handle. If you DO NOT have spark on either side with the engine unplugged from the chassis harness, the problem is more than likely under the flywheel. These twin points ignitions can be tricky to get just right, but you rarely loose both sides at once like this because they are 2 completely separate ignition systems, one for each cylinder. Also take a look at the magnets on the flywheel while you have it off. Look for rust and cracks. Report back with your findings. Hopefully something here will help.

DE

[400brian]

I have a /21 siting on the bench right now working on similar issues. Do as Dustin suggests, and then we'll go from there.

[kiedro44]

Thanks Dustin for the good advice. I tried for spark last night with the motor unplugged from the harness, and fiddled with the key and kill just in case, but nothing changed. I will put her back up on my bench and go into the flywheel again...and check back later with results.

[400brian]

It is likely your points have some corrosion on the contact surfaces, and are not passing current.

[JD600]

Hey Dan,

I've been thinking about this, and this is my current thoughts. Because you had spark (at least partial) before you went in, i'm wondering about a pinched wire or a loose solder joint on the stator that you disturbed when you had it apart. However, James T. Kirk (Brian) is the expert on the points ignition systems. Are the external coils mounted to the fan tower? I believe they need to be grounded to the fan tower in order to function, but i may be incorrect in assuming that. More than likely, if you file your points, you'll get your spark back.

DE

[kiedro44]

I had slipped sand paper between the points to "freshen" them up during this repair. It must be something with my re-assembly. I went back and more carefully examined the expanded parts diagram of the stator, and realize that for a JDX8 with my serial number, there are three wires that solder to each condenser. My set up was only two on one side (perhaps the side with weak spark) so I intend to check on that. However, in looking at the diagram pertaining to the next batch of serial #s that diagram shows two at the condenser on one side and three on the other and a slight difference in the routing causing this. More later when I get it apart to check for loose wires, etc.

[JDT]

It is possible that you actually have two problems.

The original problem was spark on only one side.

In an attempt to fix problem number one a second problem was cause by accident.

If I had to guess I would look for a bad condenser or poor soldier joint that caused the first problem.

As for the second problem maybe a bad primary coil or plug wire. nicked or pinched wire that is now grounding out and killing both sides.



If you get spark back on either side switch the two coil to stator wires, red and white, around and see what happens.

There are three possible outcomes.
1) you still have spark on only one side, the same side. Problem is from the sec coil to the plug.
2) you have no spark at all once again. Confirms that you have two issues.
3) you still have spark on one side but it switched sides. Problem is on the stator plate.

One of the guys suggested a concern for proper grounding of the secondary coil on the fan tower. This is true. You must have both coils bonded(grounded) to the engine case in order for spark to happen.

Another area that I have seen an issue many times is the spark plug wire/coil connection on the secondary coil tower. The solid core plug wire actually screws onto a threaded stud inside the tower.
This connection is vulnerable to rust and vibration. Unscrew the wire and have a look-see at the screw. If it is rusty or broken off you would have to replace the coil or clean the screw.
Also check for rusted wire inside the spark plug wire itself. The plug wire can be replaced.
Same goes for the spark plug cap on the other end of the wire. The terminal has to make a connection with the wire core of the plug wire. If it was twisted around or has rusted it can cause failed or intermittent spark.

Any spark issues can be exasperated by using "resistor" plugs. But on the same hand a properly functioning ignition system will preform just fine with R-type plugs. It is when things are just slightly off that R plugs will cause you to go bald pulling out your hair. One dirty connection may cause a little problem but 4-5 poor connections on the entire system may leave you walking home, if you were ever able to leave.

When you have the stator plate off the engine take some time and eye ball it very closely. Use a good light and even a magnifying glass to aid you in finding cracked solider joints, nicked or barred wires, missing or improperly installed insulating washers on the points, pitted points, rusted or corroded connections, etc.
Use an OHM meter to check every component and connection. The nice thing about a twin cylinder engine is any reading on the meter should be the same on either side.
If you find something that is different that you usually have found your problem.


May times guys have stated that they checked every connector and never found nothing when they unplugged them and looked them over. But when they were all done it worked just fine.
Well they did actually find the problem but they did not notice it. It was a corroded pin on one of the connectors. By simply unplugging it and plugging it back in the corrosion was partly cleaned and it works again.

The enemies can be many on these old sleds. Mouse urine, road salt, dust and dirt, melting snow, vibration, high temps from the exhaust system, mods made by previous owners, improper components used in old repairs because the OEM parts was not available 40 years later. The list is endless. Spending time looking and testing will usually reveal the suspects.