2012 copperhead 70 hp yammie 4 stroke

Discussion in 'Prop Shop' started by jonterr, Feb 27, 2014.

  1. jonterr

    jonterr I Love microskiff.com!

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    Hey guys! I know there are only a handfull of you out there with the same boat set up! I acquired this boat a few weeks ago! The motor has a 13 1/4 x 17 stainless 3 blade prop! If i run wot with tilt down, it digs the bow down really bad, if i run it at a smoothe position, wot, it runs 5200 rpm, at 35 mph, if i tilt it up a little more, i get 5600 rpm, at 38 mph, but porpises like a frikin 800 lb dolphin on a 4 ft wave!
    It just seems like the Yamaha should get more speed!
    At 5200 rpm , it seems like it has a lot more to put out!
    Any input appreciated, especially those of you with the 70 on a Copperhead!!
    Btw love the boat!
     
  2. jonterr

    jonterr I Love microskiff.com!

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    Ok
    So, i called the people at power tech, and he recomended the SCD 3 , its a 15 pitch. He said i need to be hittin 6300 rpm at wot or i could damage the engine! The prop on the boat looks Lmost new, so i will prob put it up for sale when i swap
     

  3. Gramps

    Gramps Living & Dying in 3/4 Time

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    Please define this better! Max RPM is 6300 on this motor and I want to say where it truly makes 70hp. I don't understand the "damage" statement.
     
  4. jonterr

    jonterr I Love microskiff.com!

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    All i know is Michael at Power Tech said this engine is designed to run at 6300 rpm at wot . If its wot and running at low rpm, it can cause engine damage, and running at low speeds, at lower rpms , can even caus oil pump malfunction!
    Im no boat motor person, so i dont even know if thats true!
    U can call and ask if u want!
    All i know is my boats turning 5200, and should be turnin 6300!
     
  5. jonterr

    jonterr I Love microskiff.com!

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    If anyone out there knows for sure, jump in!
    I dont want to buy a new prop if i dont need it!
    From what i understand, it will help hole shot, and raise rpm, but i dont care about hole shot!
     
  6. jonterr

    jonterr I Love microskiff.com!

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    Just got off the phone with Yamaha dealer
    He said a few hundred rpms arent going to be a big deal, but the 15 pitch would increase holeshot and raise rpms!
    Sorry to keep answering my posts!
     
  7. Gramps

    Gramps Living & Dying in 3/4 Time

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    You definitely need to get the WOT rpm's up to near max. I'd trust the guys at Powertech, they are pretty darn good at what they do.
     
  8. davefishing

    davefishing I Love microskiff.com!

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    Correctly propping an outboard is the most important factor in engine life. Here, "pitch" is the crucial element. Simply put, pitch—expressed in inches—is the distance a propeller would travel forward in one complete revolution under ideal conditions, i.e., no cavitation, slippage, or friction.

    "Underpropping", which means installing a propeller with too little pitch, can lead to over-revving the outboard, causing subsequent failure of the reed valves (one-way "gates" between the carburetors and crankcase) and even the crankshaft. Both are very expensive to replace. Conversely, "overpropping", or installing a wheel with too much pitch, can result in coking of the rings, predetonation (usually undetectable), and, so, piston failure, necessitating a costly rebuild. With the high alcohol content and generally poor quality of today's gasoline, the likelihood of this latter problem occurring is very high.
     
  9. paint it black

    paint it black Paddling away...

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    My copperhead with the 60 ran 39-41mph at 5600 rpms depending conditions and scenario. I couldn't make it porpoise if I tried. It did want to dig the nose of the motor was trimmed down, so I'll just trim way high.
     
  10. jonterr

    jonterr I Love microskiff.com!

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    Ok
    Thanks for the input!
    I guess i'll go with the SCD 3
    Ankona can save me a chunk on what i can oeder it directly from power tech!
     
  11. topnative2

    topnative2 Well-Known Member

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    Since the boat starts to plow at wot it tells me the motor is to low.
    I would raise the motor one hole and see if that helps.