No spark with 18k boot, 6.3 primary and 9k secondary.

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thunderdork

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Long time lurker. First time poster.

I have a "no spark" situation. I just purchased a 1978 xs650 special. Rode it for a couple of days. Now no start.

I checked the rotor. Has strong magnetism turned on, residual when turned off.

I tested for spark. None. I checked the resistance of the spark cable against the engine block and it read 18k. I also checked the primary ignition coils and they read 6.3 ohm. I checked the secondary coils and they both ready 9.3k. All seem high from what I ready (5k for boot, 3.9 for primary and 8k for secondary). I also noticed that the spark cable is stranded copper wire when I'm assuming its suppose to be solid...?

Should I just put in new coils, cables and boots? If so any suggestions? Want to make the ignition bullet proof as possible for a daily rider.

If it could be something else feel free to point out my ignorance (first bike).
 
That 18K spark plug cable has a bad cap. The originals were a rather odd about 9K. When they go bad, the resistance climbs (as yours has), eventually choking off the spark. Replace both of the caps with NGK LB05F's.

NGKLB05.jpg


Your plug wires are correct, they should be stranded not solid. When you get the new caps, prep the wire ends like so before installing them. It's a good idea to trim about 1/4" to 1/2" of wire off each end to get to some fresh wire. Yes, do the coil end too. Or you can get new wires as well.

PlugWireEnd.jpg
 
6.3 ohm primary is quite high. The spec of 3.9 ohms is at 20C or 68F temperature. How hot was the coil when you measured? Resistance does increase with temperature.

You should check the voltage of the battery, because it affects the ignition.
Engine off, fully charged battery...............12.4 to 12.5 volts
Engine running at idle..................13.0 to 13.4 volts
Engine running at 3000 rpm..................14.0 to 14.3 volts

If the ignition coils, plug leads, caps and points/condensers look to be very old, as in they might be original, I would just replace the whole lot with a new ignition system. If you want good spark and a reliable bike, don't use old, low voltage ignition components.

With these bikes its a must to have strong voltage and strong ignition spark.
 
Coil wasn't hot at all since I can't get the bike to start. Went ahead and put in a mat glass battery. measures 12.5v. I think the coils aren't original since the wires can just be screwed off and on with a compression cap.

I think i'm gonna go ahead and order new coils, boots and wires. Any suggestions on coils? I've seen these from mikesxs:

http://www.mikesxs.net/product/17-6805.html
http://www.mikesxs.net/product/17-6807.html

Is it worth double the price for the green XS performance coil? Or will it be a waste if I forget to turn my ignition off once when the bike isn't running (i'm not necessarily bright sometimes).

Also, I eventually will probably replace the points/rotor etc with a new system as well but can't afford it right now. Would either of those be best towards working on a new system? Either way which ignition system would you guys recommend?

Not gonna do PMA quite yet. Electric start is nice to have during a stall on a hot Texas day.
 
thunderdork said:
Coil wasn't hot at all since I can't get the bike to start. Went ahead and put in a mat glass battery. measures 12.5v. I think the coils aren't original since the wires can just be screwed off and on with a compression cap.

I think i'm gonna go ahead and order new coils, boots and wires. Any suggestions on coils? I've seen these from mikesxs:

http://www.mikesxs.net/product/17-6805.html
http://www.mikesxs.net/product/17-6807.html

Is it worth double the price for the green XS performance coil? Or will it be a waste if I forget to turn my ignition off once when the bike isn't running (i'm not necessarily bright sometimes).

Also, I eventually will probably replace the points/rotor etc with a new system as well but can't afford it right now. Would either of those be best towards working on a new system? Either way which ignition system would you guys recommend?

Not gonna do PMA quite yet. Electric start is nice to have during a stall on a hot Texas day.
Click to expand...

Those 2 coils are not good choices.

My recommendation is what you see in my Signature at the bottom of my posts. However, if you are on a low budget, you could use #17-6822 coil. Its a 4.5 ohm coil, so it will work with points. You only need to buy one of that coil, not 2 as in the stock set-up for the 78SE. If you go with the #17-6822 , you need to connect both sets of points together in parallel, and only use one capacitor, not 2.
 
I'm a noob. Not sure what "connect both sets of points together in parallel" and "use one capacitor" entails. Any resources to show how to wire it?

Your Pamco is a PMA ignition, right? If I wanted to keep my starter should I just bite the bullet and get the boyer setup?
 
Ok, just a bit of clarification. The Pamco is an ignition, A PMA or Permanent Magnet Alternator, is the alternator. Two different systems.
The PMA makes power to run the bike and charge the battery.
An ignition just makes the plugs spark.
You can run a Pamco with your stock alternator.
You can run a Boyer with your stock alternator.
You can also run either one with a PMA.
Leo
 
ah, I thought all the pamco pma's came with the pma and were required. if that's not the case then I can use a pamco ignition with the stock and then swap out the alternator later if I choose...?
 
Yes, If you look on Mike's you will find many Pamco kits. some are just the Pamco, Some are just the Pamco with E-advancer, Others have coils plug wires caps advance rods bushings, Others have the PMA as part of the kit.
There are many options depending on what you have and what you want to do.
Leo
 
Thanks! Yeah, got my eyes on one now. I did forget that I wanted to make this bike my "Doomsday" ride. So i'm gonna keep the points in it for now. Ya know, in case a nuclear EMP blows out every digital ignition :D

so I went ahead and did what retiredgentleman suggested and got the 6822 dual coil ignition. i read in another thread that you can use it with a pamco too, but if not oh well...

my only question though is about the wiring. i'm assuming by "wiring the points in parallel" means gang up the red/white wires from both points together and connect them to one side of the primary, then gang up the orange wires from both points and connect them to other side of the primary. is that correct?

also, to just run one cap I just disconnect one of the two back wires, right? since this is a single coil with two outputs it just needs the one. one cap is gonna be able to charge up fast enough to do twice as many bursts?
 
thunderdork said:
Thanks! Yeah, got my eyes on one now. I did forget that I wanted to make this bike my "Doomsday" ride. So i'm gonna keep the points in it for now. Ya know, in case a nuclear EMP blows out every digital ignition :D

so I went ahead and did what retiredgentleman suggested and got the 6822 dual coil ignition. i read in another thread that you can use it with a pamco too, but if not oh well...

my only question though is about the wiring. i'm assuming by "wiring the points in parallel" means gang up the red/white wires from both points together and connect them to one side of the primary, then gang up the orange wires from both points and connect them to other side of the primary. is that correct?

also, to just run one cap I just disconnect one of the two back wires, right? since this is a single coil with two outputs it just needs the one. one cap is gonna be able to charge up fast enough to do twice as many bursts?
Click to expand...

Yes, the red/white is the power feed from the kill switch. You really only need one red/white to connect to the coil primary. If you want to use both red/whites you can do that too.

Actually wires from the points are orange and grey. Parallel means connect both the orange and grey together on the other ignition coil terminal.

You're correct about the capacitor. The capcitor body must be connected to bare metal of frame or engine.

Edit: Be sure to reply back to let us know how your engine runs. To many lads never reply back so the story never has an ending.
 
Last edited:
Okay, got the coil and am about to wire it up. so grey and orange together and i also bunched up the two red/whites together too.

Vx2DWE1.jpg


My only question now is the coil itself has a blue wire and a black/white wire. Which one goes to which? Some people say its not horribly important but other people say it can lead up to 45% less spark.
 
Your dual output coil is what they call non polarity sensitive. This means you can hook it up either way.
The way the coil works one plug will be a positive plug one a negative plug. This means the spark jumps from the center off the plug to the outside on the negative plug. The spark jumps from the outside to the center of the plug on the positive plug, or is it just the opposite, either way the spark that jumps from the outside to the center is slightly weaker than the plug that fire from the center out.
On a low output coil, around 10-15kv it might matter. Your coil has much more output so even with one plug firing a bit weaker it won't matter.
Leo
 
Thunderdork, perhaps go to the first principles while you digest what the fellers are saying - if you rode it and then went down, it sometimes (quite often, actually) that wires come loose, earth is lost, there is dirt or corrosion in the electric that a little bit of riding pushes to exhaustion.

Battery working (don't charge with a car charger), check the earth - take them off and clean. You can do this while you are following the other things.

Keep us posted.

Anlaf
 
okay, so i don't have to re-plug anything :) So I'm getting spark. But i have to hold it 6 inches infront of my face to see and hear it. That seems kind of weak to me. Is that normal on these bikes?
 
thunderdork said:
okay, so i don't have to re-plug anything :) So I'm getting spark. But i have to hold it 6 inches infront of my face to see and hear it. That seems kind of weak to me. Is that normal on these bikes?
Click to expand...

This is what my spark looks like. Its blue not yellow. Looking at yours in a darkened garage, what colour do you see? Does the engine start easily and run normally? Do you have one capacitor black lead connected?

That coil is rated at 37K volts. You could have higher than normal resistance somewhere in the ignition coil primary path.

Take some voltage readings. Put your VOM negative probe on the battery negative terminal. Start the engine and have it idling at 1200 or 1300 rpm. With the VOM positive probe, measure at 3 places....................the battery + terminal, one terminal of the coil primary, and the other terminal of the coil primary.
 

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ah, i think i forgot and plugged both black wires from the new condenser in. I'll unplug one and give it a go once the rain passes down here.

the good news is that I was able to get it kick started a couple times if i kept the throttle open. got it going twice for 30 seconds. but once it dies it only tries to kick over a couple times then nothing. carbs?
 
thunderdork said:
ah, i think i forgot and plugged both black wires from the new condenser in. I'll unplug one and give it a go once the rain passes down here.

the good news is that I was able to get it kick started a couple times if i kept the throttle open. got it going twice for 30 seconds. but once it dies it only tries to kick over a couple times then nothing. carbs?
Click to expand...

If you purchased an old bike, and don't know the history of it, you must take the carbs apart and check for cleanliness, float levels, jet size as compared to stock size (see Carb Guide in Tech section).

If you want to have success with your bike...................need good voltage (battery and charging working), ignition working properly, good compression and carbs cleaned/tuned. If you have anyone of these absent, then you will just go around in circles, and solve nothing.
 

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