1973 85 johnson tach question

Discussion in 'Bubba's Outboards' started by fishnohio, Apr 1, 2008.

  1. fishnohio

    fishnohio New Member

    Messages:
    58
    State:
    Middletown,Ohio
    i have a 1989 winner bass boat with a 1973 85 johnson on it the boat came with a yamaha motor on it originally, and the time has come to get a new prop ( thanks to a rock in the water ) and the prop is not marked, so i need to see what my w.o.t rpm's are in order to select the proper propeller pitch. so i have a couple questions i guess, what are the recommended w.o.t rpm's for my motor? and does johnson and yamaha use different tach pulses and if so is there a way to change it so the my tach will work? or is there some sort of device to hook up temporarily to see what my w.o.t rpm's are on the lake?

    signed
    irritated in Ohio....LOL
     
  2. slimdaddy

    slimdaddy Well-Known Member

    Messages:
    2,603
    State:
    Nelsonville, Oh
    Name:
    Keith
    4500-5500 rpms wot operating range 85 hp at 5000 rpms thats whats in the manual i have a 74 85 hp manual
     

  3. slimdaddy

    slimdaddy Well-Known Member

    Messages:
    2,603
    State:
    Nelsonville, Oh
    Name:
    Keith
    also the prop that came with 13 1/4 dia 17 picth
     
  4. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    You can run that engine up to 58 hundred without any ill affects. I ran one just like it for years. Now not knowing the weight and size of your boat I would guess that the 17 pitch would work and maybe with a cup in it to help increase fuel milage. As for the tach I think it is a 6 pulse setting. Look on the back of the tach and it should have a control to set the pulse setting and I do think yahamma was the same.