One side not firing. What to look for?

[jchrisk1]

78 SE. Stock ignition and charging system.

Okay, so I've been riding my bike for about two weeks with no issues, other than a little lean on the pilot circuit. Until today.
This morning I got caught in the rain again on my way to work and when I was almost there it cut out and lost speed. I pulled over and it died and I started checking some things and found it wasn't getting any spark on the right side. My boss came by with the trailer and we hauled it to his house then went to work. After work I got to checking what I could with a phillips a test light and a few other misc. tools.
What I found was, the left side wire to the points is hot constantly as I turn the crank and the right side is dead. The light is on when I touch each wire on each coil.
All i've got is an analog meter so I don't know how accurate it will be to check the coils, but that is what I'm going to do now.
Other than that, I don't know what else to do. So if anyone can help, please do. When I do a search, I'm mostly coming up with fuel problems or TCI ignitions.

 

[shotgunjoe]

Check for power at the points, thats a good place to start.

 

[jchrisk1]

Power on the left. No power on the right.

 

[azman857]

Id start with cleaning and setting the points. If that don't work grab the multimeter and check High side(coil wire) and ground for continuity. Have the meter on high ohms. If good, check the low side (where the power and points connect), wires off and check continuity(low ohms). The caps at the end of the plug wires are good?

 

[jchrisk1]

Sorry, my electrical is minimal. I don't understand high side and low side.

I put my leads on the orange and brown and have continuity on both coils. Don't know if that means anything or not. And, I put a lead on orange and on spark plug cap and got about 10k on the right side (problem side), and about 14k on the left side. Again, I don't know if this is the correct way of doing things. And it is all being done with an analog meter.

Could you explain in more detail please.

 

[azman857]

Digital or analog meter makes no difference. Coils should be disconnected when checking. High (tension) side is the high voltage (sparkplug) side. Low tension(primary)is the power from the bike side. Do you have any service manuals? Check out biker.net if you don't. It has a Factory Service manual you can download.

 

[shotgunjoe]

When checking for power at the points you have to turn the motor over. By hand is best, pull the spark plugs, makes it easier. Only one side gets power at a time.

 

[azman857]

When you say power to the left and not right, is that from the red/white wire? Disconnected from the coils? Ignition switch on and shut off (handlebar) in run position. Should get really close to battery voltage.

 

[jchrisk1]

Thanks. My Haynes manual doesn't tell how to check coils. It says to take it to a shop.
I will check out biker.net.

I think I may only have a loose connection somewhere. After screwing around and checking things, if you want to call it that, it now has power to the right side points again and is working. Now I am afraid to ride it very far for fear of getting stranded. I guess I will tighten up all of the connections and hope for the best. Meanwhile, I'll study up on how to check everything in case it happens again.

I am planning on upgrading to a pamco with new coil next week if I can get one before they sell out. So hopefully that will end this problem.

 

[jchrisk1]

When checking for power at the points you have to turn the motor over. By hand is best, pull the spark plugs, makes it easier. Only one side gets power at a time.

That is what I was doing, but that is where the left side had power continuously and the right side had nothing at all. It stayed this way as I turned the rotor by hand.

 

[jchrisk1]

When you say power to the left and not right, is that from the red/white wire? Disconnected from the coils? Ignition switch on and shut off (handlebar) in run position. Should get really close to battery voltage.

Not at the red wire. I was only putting my test light (all I had at the time) on the points connection, ignition on, run position, turning rotor by hand. When I put the test light on the coil wires, orange and brown, everything connected and on, it was lighted.

 

[shotgunjoe]

Sounds like the points gap is off to me. The power should go on and off for both sides. How it can even run on ONE cylinder stumps me.

 

[shotgunjoe]

One side of your test light should be to ground, the other end touching the points where the wire connects.

 

[jchrisk1]

I will check the gap again and see if it is out. It wouldn't run on one cylinder, at least not more than a crappy idle. They are both firing now. Somehow. I didn't really do anything but disconnect and reconnect wires.

 

[hmusket]

This might have happened because of the rain, moisture under the points cover? I would also check the spark plug wires and caps to see if moisture could have effected them. Whenever I get an old bike one of the first things I do is put in new plugs and replace the spark plug wires and caps.

 

[shotgunjoe]

Sounds like moisture to me too. Where, I don't know. While its apart, good time to clean connections, and out dialectic grease on them.

 

[jchrisk1]

I think it was moisture or a loose connection. Most likely moisture.

I cleaned the points, reset the gap, reset the timing, and tightened all of the connections. Put About 90 miles on it today. All was good. Running like a champ.

Thanks for all of your help.

Only problem today was some dumb broad looking through her purse and almost ran me over at a stop light. If you know how to fix that, let me know.

 

[shotgunjoe]

Loud pipes save lives!