In the last month I've helped two different people sort out unusual problems with their Dyna electronic ignitions. I thought perhaps the information might be useful to someone else.
Bike #1:
The patient was a '78 GS1000 with brand-new Dyna ignition, coils and wires installed by the owner (one of the stock coils was bad, so he decided to go ahead and upgrade the ignition system). The bike started, but ran very, very badly, with lots of unburned and half-burned gas in the air. When we hooked up a timing light, the flashing was all over the place, ony firing in the correct spot once in a while. Both the 1/4 and 2/3 sides were affected.
After verifying voltage at the coil (good) we started to retrace the installation steps. The triggers were hooked up to the coils correctly, but the red power wire to the Dyna ignition was hooked into one of the stator wires.
So basically, the Dyna ignition was getting AC voltage from one leg of the stator instead of switched 12V DC.
I'm amazed it worked at all...
This error was traceable to very poor instructions from Dyna -- they specified a green/white wire which doesn't exist on a GS, so the owner ended up hooking up the Dyna's power wire to the white/green stator wire. An understandable error, really.
So with that corrected, the bike ran quite a bit better. But still not right. After a bit more investigation with a timing light, we found that the #3 and #4 spark plug leads had gotten switched around somewhere along the line.
Sorted!
Lessons learned:
- Never trust the instructions completely, especially when you're dealing with an aftermarket part for a 32 year old bike. Understand and think in terms of the principles of what you're doing.
- It's never just one problem at a time on an older bike. Review all systems that could affect the problem.
- Sometimes you gotta get your hands dirty. This would have been nearly impossible to diagnose without laying hands on the bike. It also helped to have a lot of GS experience -- I already knew that a white/green wire was a stator wire, which helped me understand as soon as I saw it that the ignition was hooked up to the wrong wire.
Bike #2:
The patient was a 1979 GS850G, converted to Dyna ignition and coils about a year ago by the owner. The bike had been running very nicely, but was recently starting to drop spark on the 1/4 cylinders after 5 minutes or so on the road.
One important clue was that the bike would sometimes emit a "poof!" when the key was shut off.
After double-checking all the wiring (all good, fixed a few unrelated issues), coil impedance, etc. we fired it up and checked timing with a timing light. Everything looked good (advancer working, timing spot-on), and after ten minutes of idling (yes, we had a fan in front of the engine to prevent overheating) it still hadn't acted up. Our remaining theory was that the problem had to be a coil or an ignition pickup that was overheating under load and higher RPM.
On a hunch, I left the ignition cover off and we went for a ride. The bike ran perfectly for the 20 minute ride into the next town. Hmmmmmmm...
We pulled over in a vacant parking lot, replaced the ignition cover, and got distracted for a few minutes by the five cops who showed up suddenly (turns out there was a dangerous character on the loose that might have run our way). After establishing that neither of us was a slender black man with a weapon (not even close), we mounted up, and... the GS850 was running like crap once again. No spark on 1/4.
We removed the ignition cover, fired up the malfunctioning bike, and limped back onto the road. Within a minute, the bike took off with a lurch and ran sweetly all the way back.
Diagnosis: Bad 1/4 ignition pickup -- when the engine heated up, the ignition pickup stopped working. With the ignition cover off, the pickup could stay cool out in the airstream (it was a chilly day as well). With the cover on, enough heat was retained to reproduce the problem. The owner is attempting to sort things out with Dyna...
Lessons learned:
- Don't just assume newer parts are good
- Understand how the physical environment -- heat, vibration, etc. -- can affect parts.
- Understand the physics of how things work. The "poof" when shutting off the key was an important clue that the 1/4 coil was actually working. When the key was shut off, it cut off power to the coil, so the field inside the coil collapsed and made one last spark.
- Triple-check everything you see whenever you get a chance, especially on old bikes. We caught and fixed a few other wiring problems along the way that will likely save the owner a lot of future trouble.
- Small-town cops are a little excitable.
Bike #1:
The patient was a '78 GS1000 with brand-new Dyna ignition, coils and wires installed by the owner (one of the stock coils was bad, so he decided to go ahead and upgrade the ignition system). The bike started, but ran very, very badly, with lots of unburned and half-burned gas in the air. When we hooked up a timing light, the flashing was all over the place, ony firing in the correct spot once in a while. Both the 1/4 and 2/3 sides were affected.
After verifying voltage at the coil (good) we started to retrace the installation steps. The triggers were hooked up to the coils correctly, but the red power wire to the Dyna ignition was hooked into one of the stator wires.
So basically, the Dyna ignition was getting AC voltage from one leg of the stator instead of switched 12V DC.
I'm amazed it worked at all...This error was traceable to very poor instructions from Dyna -- they specified a green/white wire which doesn't exist on a GS, so the owner ended up hooking up the Dyna's power wire to the white/green stator wire. An understandable error, really.
So with that corrected, the bike ran quite a bit better. But still not right. After a bit more investigation with a timing light, we found that the #3 and #4 spark plug leads had gotten switched around somewhere along the line.
Sorted!
Lessons learned:
- Never trust the instructions completely, especially when you're dealing with an aftermarket part for a 32 year old bike. Understand and think in terms of the principles of what you're doing.
- It's never just one problem at a time on an older bike. Review all systems that could affect the problem.
- Sometimes you gotta get your hands dirty. This would have been nearly impossible to diagnose without laying hands on the bike. It also helped to have a lot of GS experience -- I already knew that a white/green wire was a stator wire, which helped me understand as soon as I saw it that the ignition was hooked up to the wrong wire.
Bike #2:
The patient was a 1979 GS850G, converted to Dyna ignition and coils about a year ago by the owner. The bike had been running very nicely, but was recently starting to drop spark on the 1/4 cylinders after 5 minutes or so on the road.
One important clue was that the bike would sometimes emit a "poof!" when the key was shut off.
After double-checking all the wiring (all good, fixed a few unrelated issues), coil impedance, etc. we fired it up and checked timing with a timing light. Everything looked good (advancer working, timing spot-on), and after ten minutes of idling (yes, we had a fan in front of the engine to prevent overheating) it still hadn't acted up. Our remaining theory was that the problem had to be a coil or an ignition pickup that was overheating under load and higher RPM.
On a hunch, I left the ignition cover off and we went for a ride. The bike ran perfectly for the 20 minute ride into the next town. Hmmmmmmm...
We pulled over in a vacant parking lot, replaced the ignition cover, and got distracted for a few minutes by the five cops who showed up suddenly (turns out there was a dangerous character on the loose that might have run our way). After establishing that neither of us was a slender black man with a weapon (not even close), we mounted up, and... the GS850 was running like crap once again. No spark on 1/4.
We removed the ignition cover, fired up the malfunctioning bike, and limped back onto the road. Within a minute, the bike took off with a lurch and ran sweetly all the way back.
Diagnosis: Bad 1/4 ignition pickup -- when the engine heated up, the ignition pickup stopped working. With the ignition cover off, the pickup could stay cool out in the airstream (it was a chilly day as well). With the cover on, enough heat was retained to reproduce the problem. The owner is attempting to sort things out with Dyna...
Lessons learned:
- Don't just assume newer parts are good
- Understand how the physical environment -- heat, vibration, etc. -- can affect parts.
- Understand the physics of how things work. The "poof" when shutting off the key was an important clue that the 1/4 coil was actually working. When the key was shut off, it cut off power to the coil, so the field inside the coil collapsed and made one last spark.
- Triple-check everything you see whenever you get a chance, especially on old bikes. We caught and fixed a few other wiring problems along the way that will likely save the owner a lot of future trouble.
- Small-town cops are a little excitable.
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