What prop for my Honda 15hp four-stroke to go faster?

Discussion in 'Prop Shop' started by mkhsurf, Feb 4, 2010.

  1. mkhsurf

    mkhsurf I Love microskiff.com!

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    BF15 honda on my classic. Just want a little more top end speed. wondering what my options are and how much a new prop could help?
    Suggestions?
    Thanks
     
  2. Brett

    Brett > PRO STAFF <

    First the specs

    Type  4-Stroke SOHC 2 Cylinder/4 Valves
    Displacement 350 cc (21.4 cubic inches)
    Bore & Stroke 59 mm x 64 mm (2.3 x 2.5 inches)
    Full Throttle RPM Range 4,500-5,500 RPM
    Rated Power 15 HP @ 5,000 RPM
    Cooling System Water Cooled
    Fuel Delivery 1 Carburetor
    Ignition System PGM-IG
    Starting System Electric/Recoil
    Exhaust Through Hub
    Lubrication Wet Sump
    Trim Range 4 Stage 8°-12°-16°-20°
    Tilt Range 72°
    Drive
    Gear Ratio 2.08:1

    Then the process:

    1) Install a tachometer
    2) Run the boat with a light load and determine the full throttle rpm with the existing prop.
    3) A change of 1 inch of pitch will produce a change of about 200 rpm
        more pitch means less rpms, less pitch means more rpms
    4) Buy a prop with the pitch that will give you 5200-5400 rpm at full throttle.

    Previous post:

    http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1260548288/1#1
     

  3. noeettica

    noeettica Well-Known Member

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    For now forget the prop !

    The motor is the same displacement as a 20 Hp I bet a carb change will wake it up then follow brett's sugestions ... That motor should be able to Run a 12.5 pitch prop ...

    Keep us posted :)

    Dave
     
  4. mkhsurf

    mkhsurf I Love microskiff.com!

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    Thanks for the info.. I hadnt even thought about carb adjustments. Thanks guys. Is there a carb kit you had in mind? What basic components would I need to wake her up!!?
     
  5. Brett

    Brett > PRO STAFF <

    You get to enjoy playing "Whats different in these two pictures?"

    http://www.boats.net/parts/search/Honda/Outboard%20Engine/parts.html

    Find your year and model
    then check the carb, block, head and exhaust part numbers
    against the part numbers of the same year 20 hp Honda.
    Those parts that have different numbers are the ones to replace.