[Early_S_Man]

Jim,

The best way to test coil and CDI-unit is by putting the engine on an ignition scope such as an old Sun machine ... or conventional oscilloscope with a special-purpose 40 kV - rated high Voltage probe.

Bench testing can be done by powering the CDI-unit from a 13.8 Volt power supply of at least 3 Amp capacity. A substitute pulse source [to replace distributor & points] can be assembled from a 5 Volt or 12 Volt reed relay and powered by a suiable 5 or 12 Volt wall transformer with full-wave bridge added -- giving a 120 Hz pulse train.

If you know a Ham-radio or electronics enthusiast, he/she would be able to test the CDI-unit and coil together. Don't test the CDI and coil without a load on the coil! A suitable load for the coil consists of an old, tested-good, spark plug wire and a new or used spark plug with attached ground lead.

Grounding of the relay/fuse/regulator panel -- specifically the grounding of the CDI-unit -- is VERY CRITICAL!!! I usually run a heavy braided ground strap equivalent to an 8 ga wire from under one of the mounting bolts for the CDI to under one of the fender mounting bolts for the relay panel. Remove the CDI-unit and clean the grounding 1/4" Faston tabs -- remove from the magnesium case and clean both under the tab location on the case and the tab itself with vinegar and stainless steel toothbrush, followed by brushing and rinsing with water. When everything has dried, apply silicone grease coating to Faston tab and re-attach to CDI case. The four-wire female connections to the CDI-unt can be cleaned with vinegar and have the sides of the connectors that slide onto the male Faston tabs crimped slightly to make a better connection. Don't close the gaps on each side to zero, just slightly crimp! The three wires in the special three-wire connector can be slid out an inch or so by lubricating the wires at the back side with silicone spray, then pulling the wires all out, gently, with needle-nose pliers.