that tach is for a single cyl motor.
your best bet is gonna be a trail tech vapor.
they are back lit with tach,speedo,shift lights,temp sensor,hrs meter,etc.(digital display)
you can find them on ebay for around 100.00 or so
the thing about a banshee motor is its what is called a dead fire motor.
both cyls fire at the same time.
and the trail tech has an adjustment for this.
when you get the vapor and are setting it up it will ask you what the ppr(pulse per revoloution)is and set it to 2.
the only disadvantage to the vapor is you need a small 12v power source for it.
Dan