Ignitions problems i almost always recommend taking in to a professional because the parts are not returnable. The parts are usually expensive and if you buy one of the wrong parts you have just spent 2-3 times more then it would have cost to just have a pro do it.
To properly test the equipment you need specialized equipment, i use a DVA meter, could also use an oscilloscope. It could also be done with a DVM on the Ohms setting but this doesnt always give reliable results because there are too many variables for most to account for that would throw off the reading on a DVM. I make these kind of repairs regularly and dont even get it right a lot of time testing with only the DVM and is why i use the DVA meter instead.
First make sure the kill wire is unplugged where it goes into the CDI unit. Dont know exactly how that switch was removed so need to eliminate the possibility of shorts.
If you want to try the DVM the ignition coil should have .5-.62 ohms resistance on the primary circuit and 6.4-9.6 kOhms on the secondary circuit, the pulse coil should have 120-132 ohms, and the exciter coil should have 297-363 Ohms. If you have confirmed all those readings then all that is left is the CDI unit, replace that.
Dont know that wire colors of these older motors, thats something you will have to figure out just by looking where the wires lead to.
