KA--POW In Flight

This morning I was doing some test at 8000 DA and after completion I felt a little (very little) serge, so with the runway in sight I decided to turn off my EI switch, then EI back on, then the Mag off then Mag back on and no problem. Thought I would do it again and look at my RPM to see the drop. Switched the EI off leaving the Mag on and KA--POW. It got my attention real fast. I turned the EI back on and all was well. Thought it would be best to land and check out things... I believe but cant verify my altitude may have been 6000', (but I know it was NOT any lower) full power and LEAN 50* rich of peak (at 8000 DA). Just did annual 2 weeks earlier and Mag and EI both checked out ok. Also cleaned top and bottom plugs and checked gap. Also cleaned and verified injectors were ok.
N65KW - IO-320 Mattituck - Non builder
ANY IDEAS ON MY NEXT STEP

Key Switch or Toggles

Larry, I had that problem at first with Slick on left and Electroair
on the right. With key switch would get backfire when checking mags.
Was told toggle switches would solve problem. Don't remember exactly but
something with delay in firing when switching. Switched to two toggle
switches and zero chance of backfire.

Type of ignition switch, key or toggles?

Yes, sounds like you have the problem with the position of the EI on the switch such that the EI goes through off when checking the mag. You can reverse the position of the ignition leads on the back of the switch or use toggle switches. If you have room on the panel Electro Air makes a really nice panel with the switches for ignition and the starter in a nice little 2"x3" or so panel that looks really nice and is properly labeled.

Vic

KA--POW SWITCH OR TOGGLE

I have toggle switches... I have had backfire on other planes (LongEZ) with key switch and did install toggles and no problem... But in flight I have not ever had that. It does get your attention. I am sure the little prop in front stopped for a microsecond. thanks for the help