Settings and reading tachometer on a KE100

I'm want to check the RPMs on my KE100 when it is at its top speed of 55mph. The bike does not have techometer. I have this old Suntune dwell/ tec meter. Can it be used to measure RPMs on a 6 volt 2 stroke? What switch settings and would there be a multiplier. 

On a 4 cyl. you get 2 sparks by 1 crank rotation, on 6 cyl. you get 3 sparks.
I would prever the 4/8 cyl. reading setting.