SenDec Iductive Tach RPM monitor? 1977 Evinrude 15

[1968dart]

Hey everyone I'm trying to figure out what model of surface mount SenDec rpm gauge to get for my 1977 Evinrude 15. I need to know if this engine's plugs fire 2 times for every 1 rpm? or if it's it 1 spark per 1 rpm?
Any help would be appreciated thanks.

Herd about these from FAQ section on this forum, I would like to try one. Has anyone had any experience with these?
www.sendec.com

 

[pvanv]

Re: SenDec Iductive Tach RPM monitor? 1977 Evinrude 15

That's a 2-cylinder 2-stroke. Each cylinder fires with each revolution of the motor. So 1,000 RPM gives 1,000 lights of the spark plug per minute.