#### pamcopete

##### Ride.Enjoy.Life is Simple

This is a plot from a clamp on current probe measuring the current draw for an GS electronic ignition and a pair of 3.0 Ohm Accel yellow coils. They measured at 3.3 ohms cold. This is a 4 cylinder wasted spark engine so it is firing 2 times per revolution. The same as a 2 Cylinder.

The scale is 1 amp per division starting at the small arrow marked with a 1. The average current is 2.47 amps with a peak at 3.1 amps. Data taken at 2500 RPM.

Well, there are a few missing bits of information here.

1. Is this a crank based or a cam based ignition?

2. Is the depicted current for both coils or just one coil?

3. What is the dwell angle? If dynamic, then at 2500 RPM.

4. What is the supply voltage?

A cam based wasted spark ignition fires two times per revolution of the cam or once per revolution of the crank in the case of a twin 360 degree crank engine, like the XS650. A four cylinder wasted spark system will fire two times per revolution of the crank or four time per revolution of the cam, so the averages will be different. In other words, the twin 360 will fire every 360 degrees of the crank, but the four cylinder will fire every 180 degrees of the crank, or every 90 degrees of the cam. So, the average current should be about double for a four cylinder wasted spark as compared to a two cylinder 360 crank wasted spark.

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