V35TT Dyna S Ignition Problems

Technical Small Block V Twins (not new V7s)
1

Hi. I’ve just bought the bike and I knew it had no spark. The previous owner had spent a lot of money having a Dyna S system fitted. He said it ran for a bit and then it didn’t. The system seems to be wired up right. There is 12 volts to the new coils, but I have no spark.The kill switch is working. Can you troubleshoot these or am I best starting again?

2

Testing a Dyna S ignition involves checking for 12V power to the module, verifying that the module switches (triggers) by measuring voltage changes at the coil, and testing coil resistance. Key tests include confirming (0.8 \text{–} 1.4\text{V}) on the coil (-) when the rotor is away from the sensor, and nearly battery voltage when aligned. If spark is absent, check for (12\text{V}) on the red wire. [1, 2]

Pre-Test Checks

  • Battery Power: Ensure the battery is fully charged.
  • Visual Inspection: Look for broken wires, loose connections, or melted insulation.
  • Rotor Gap: The gap between the rotor and sensor should be (0.025\text{–}0.040) inches. [1, 2, 3]

Testing the Dyna S Module

  1. Check Power: Turn the ignition switch on. Use a voltmeter to confirm (12\text{V}) is present at the red wire connected to the coil (+) terminal.
  2. Voltage Check (Triggering):
  • Rotate the engine so the magnet in the rotor is away from the sensors.
  • Measure the voltage between ground and the coil (-) terminal. It should read roughly (0.8 \text{–} 1.4\text{V}).
  • Rotate the engine so the magnet points directly at the sensor. The voltage should jump to near battery voltage.
  • If the voltage does not change, the module is likely faulty.
  1. Swap Module Test (Dual fire): If one cylinder is dead, swap the ignition module
3

Nick. That is fantastic thank you. When I bought the bike, I knew I was a bit out of my comfort zone. I still am, but a little less. Anyway, the air gap on one side was massive. So I fixed that. There is 12v to the red wire. With the magnet pointing away from the pick ups, I have 12v on all the coil terminals. So, that seems bad. Both coils have a primary resistance of 1.7 ohms, which is less than what they reccomend for the system. Not sure is that is bad. The secondary resistance was 13,000 ohms on one side. On the other side, I could not get a reading (>20,000 ohms]. I assume this coil is bad, but I am unsure if one bad coil would knock out the whole thing. Thoughts anybody? If I had the bits, I would have put the points back in​:joy: