Thread: Setup Help

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  1. #1
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    Setup Help

    I have an Alumacraft 1860 (non pad style hull). Just put a new Mercury 90 4 stroke on it. 6” jackplate. Came with a 21p Laser II 3 blade prop. Can only hit 5400 rpms at 42mph. I have gradually raised jackplate to halfway to get to this point. Any suggestions? Should I drop down to a 19p prop? Max for this motor is 6000 rpm.

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    #2
    Quote Originally Posted by RyanJ View Post
    I have an Alumacraft 1860 (non pad style hull). Just put a new Mercury 90 4 stroke on it. 6” jackplate. Came with a 21p Laser II 3 blade prop. Can only hit 5400 rpms at 42mph. I have gradually raised jackplate to halfway to get to this point. Any suggestions? Should I drop down to a 19p prop? Max for this motor is 6000 rpm.

    when I had a 90 yamaha 2 stroke I ran a 18 pitch prop

  3. Member
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    #3
    1 inch pitch = 200rpm, so 18 it is. I spent a ton of time and money fooling with a JP on a Lowe 18HP and got 2mph and a ton of Squirrel. Jerk that JP off, mount your motor at hole 3, and get a Spitfire X7. Thrilled with mine.
    2015 Ranger RT188 DC; BassCat Storage Box; Mercury Optimax 115ProXS;
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  4. Member
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    #4
    It is handling great right now not squirelly at all. Decent hole shot. Bites nice in the turns. Really just need the rpms up. Great water pressure wide open 25 psi….

  5. Member
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    #5
    Quote Originally Posted by GeauxTide View Post
    1 inch pitch = 200rpm, so 18 it is. I spent a ton of time and money fooling with a JP on a Lowe 18HP and got 2mph and a ton of Squirrel. Jerk that JP off, mount your motor at hole 3, and get a Spitfire X7. Thrilled with mine.
    I’d have to get the X7 in a 17 or 19 pitch dont see an 18.

  6. Member tcesni's Avatar
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    #6
    Definitely too much pitch in the prop.
    2018 Ranger RT188 SC Black/115 hp Yamaha SHO 4-stroke; Garmin LVS34 - north
    2018 Ranger RT188 DC Black/115 hp Merc Pro XS 4-stroke; Garmin LVS34 - south
    14' Mirrorcraft tin boat (ancient) with a 9.9 Mercury 4-stroke, no electronics; catches fish anyway

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    #7
    Keep going up with the motor before you drop any money on re-propping. Just because the jack plate is half way doesn't mean the p2p isn't still too deep. Keep raising and keep an eye on the water pressure.

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    #8
    Quote Originally Posted by AndrewM-Fishing View Post
    Keep going up with the motor before you drop any money on re-propping. Just because the jack plate is half way doesn't mean the p2p isn't still too deep. Keep raising and keep an eye on the water pressure.
    Looks like it is at about a 5” difference right now. Seems crazy jackplate needs to be up so high to even get to 3.5”.

  9. Member
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    #9
    Mount the motor up one or two holes on the jack plate if raising the plate works. I don't have the same hull by my PT170 with a 90-2s is 1.75 p2p. Holeshot is basically instant and top end is about 45 with a 21p 3blade @ 5300rpm (max5500).

  10. Member
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    #10
    Just an update for anyone following:
    Emailed back and forth with Ken at PropGods. He recommends a Powertech PTR3 in 19pitch. He let's you try out and if don't work just pay $40.00 to return. Don't sound bad to me!