EGT 200 f increase and 500 RPM drop on mag check

How many hours since your carbs were rebuilt?

I helped a friend a year ago with excessive mag drop after ruling out ignition it turned out the carbs needed cleaning and new o-rings. Just cleaning the idle jets helped some but a rebuild solved the problem. So the excessive rpm drop was mixture related.

My thoughts are that a Mag Check is Ignition (Spark) related.
Nothing fuel-related changes when you shut OFF a Mag.
When a plug misfires, the fuel mixture is igniting as it passes the glowing EGT Sensor producing the EGT Increase.

Are you also experiencing some roughness with the RPM decrease/ EGT Increase?

Bill Hertzel wrote:

My thoughts are that a Mag Check is Ignition (Spark) related.
Nothing fuel-related changes when you shut OFF a Mag.
When a plug misfires, the fuel mixture is igniting as it passes the glowing EGT Sensor producing the EGT Increase.

Are you also experiencing some roughness with the RPM decrease/ EGT Increase?

Hi Bill, this post by Paul is about my trike. To answer your question, yes, we are experiencing some roughness with the RPM decrease/EGT increase on the A side mag check. 

I agree with your assessment, but finding the spark issue has been tough. All resistance values are within tolerance for respective components. All new plugs and caps. Swapping the control modules doesn’t change issue on A ignition side. Thoughts on finding spark issue? Thanks 

Garrett Wysocki wrote:

I helped a friend a year ago with excessive mag drop after ruling out ignition it turned out the carbs needed cleaning and new o-rings. Just cleaning the idle jets helped some but a rebuild solved the problem. So the excessive rpm drop was mixture related.

Wouldn’t carb related be on both mag sides and not just one, given wiring setup?