i have a 1990 merc 40hp classic ,2 stroke 4 cylinder...what should the rpm be at wot ?..currently 5200 rpm..prop is 13 pitch...and this is being measured with a scan tool from work...i am currently looking into a tach and wiring (5 pin) but my dealer is having a hard time finding what i need...does any one know the #of poles i should have or be using for the tach..
