I just read through this thread with great interest, as I've been dealing with a no-start on an Alpha Sport Summit 180 that is bone stock and unmolested, but sat for two years.
I've run all the tests you suggested at the CDI connectors with the CDI unplugged and finally plugged in. My results are noted below, and I'm hoping you can give me some direction in regard to the final test note...
Originally Posted by LynnEdwards
1) Unplug the CDI. Turn the ignition switch on. Set all kill switches the the "run" position. In the wiring harness, look to see if you have a wire on the kill switch pin. If you do, measure the resistance of the kill switch pin to the ground pin on the 20K ohm scale. It should read infinite ohms same as when the meter leads are hanging free and not touching anything). It should not read zero ohms (shorted). Found shorted. Repaired broken connection in tail light socket. Now, with parking brake engaged, infinite ohms (proper reading)
2) Leave the CDI unplugged, and the ignition switch in the "on" position. Use a meter to measure the DC voltage on the pin labeled "AC ignition power" in the wiring harness to the ground wire on the 2K ohm scale. You should read battery voltage (12 volts). What do you measure? 12 V. This is a DC CDI.
3) Leave the CDI unplugged. Use a meter to measure the resistance of the "Ignition Trigger Pulse" pin in the wiring harness to the ground wire on the 2K ohm scale. You should read approximately 150 ohms. What do you measure? 150 Ohms (proper reading).
4) Set your meter down to the lowest scale you have for measuring AC volts. 2 volts would be ideal, but some meters don't go that low. In that case use the lowest scale you have. While cranking the engine, measure the voltage on the Ignition Trigger Pulse pin in the wiring harness to the ground pin. You should measure 0.2 to 0.5 volts AC. What do you measure? .3 V AC (proper reading).
5) Now plug the CDI back in. Measure the AC voltage on the Ignition Coil pin to the ground pin using the 200 volt scale. If you have to, use a sewing pin to poke through the wire insulation and then put the meter probe on the sewing pin. But don't hold your fingers on the connection during the next test - there may be high voltage here when the engine is turning. With the ignition on and all kill switches set to the "run" position, crank the starter motor. You should see voltages bouncing around at random values and the meter captures all or part of a spark event. What do you see? Nothing. Nada. Please note that I have replaced the original mud-packed stator, magneto cover, and pickup with a new assembly after seeing only 6 V AC (while cranking) on just two of the three wires (phases) coming from the stator windings, and .99 V AC on the other. I expected more voltage - equal voltage - and on all three phases. However, with the new parts installed I have near identical readings to the old unit, if a little more equal between the two phases that give 6 volts. I assume I'm misreading something in spite of multiple tests, and that the new part is good (though I may be wrong to assume so). If so, is there any conclusion to be drawn other than a bad CDI? I assume the CDI ignores the rectifier in producing AC voltage for the coil. Am I incorrect on any point?
Any assistance is greatly appreciated!