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  1. #1
    Member
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    Dec 2005
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    Panama City
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    2,163

    Yamaha 70 four stroke on RT178 question

    Just purchased a 2015 RT 178 Ranger w/ 70 four stroke. It has a Solas 3441-138-13. I assume 13 pitch. Never had this small of a motor before. Took it out for the first time and it hit 7000 rpm's pretty quick. With two people it got out of the hole way faster than I thought it would. Found a chart that said max is 4500 - 5500. Is this true? If the tach is correct what pitch would be good?


    Have a good one and thank God for it!

  2. Member
    Join Date
    Oct 2015
    Location
    Louisiana
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    321
    #2
    I don't know anything about this motor but I would think it has a rev limiter on it to keep the RPM from going that high. Here's a thread that may help you. https://www.bbcboards.net/showthread.php?t=815323

  3. Member Panama's Avatar
    Join Date
    Apr 2009
    Location
    Southern USA
    Posts
    3,660
    #3
    I think 6300 is max RPM
    Prop it to where you get as close as you can to the max RPM at full throttle. These motors still develop power and like it up close to max with right prop.

    Get an owners manual and check it for proper information and don't go by what I say or others say.... get an owners manual...even if you get one you have to download.
    ----------------------------
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    long after the sweetness of low price is forgotten - Benjamin Franklin

    2013 RANGER RT188 - YAMAHA F115 - ULTREX - LOWRANCE GRAPHS
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  4. Member
    Join Date
    Oct 2012
    Location
    Pelham, AL
    Posts
    2,151
    #4
    Look at the Yamaha Bulletins under the 70hp engine. An Alumacraft 175 is listed with a 15" prop, giving 6250 WOT. I would consider a 4 blade with the weight of your hull with the batts and gas tank being in the back of the hull. My Laser 20 hasn't been used since I got the Spitfire.
    2015 Ranger RT188 DC; BassCat Storage Box; Mercury Optimax 115ProXS;
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    TM Eliminator; Helix 7 G2N SI Combo F/R; HydroWave KVD; BBT 4" Angled Bow Mount; Durasafe Locks for Electronics and Ultrex;
    Twist Step Boarding Ladder; EZEE Step ES1; BAC RAC Rod Storage; Motor Mate Transom Saver