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Thread: Building a Super Mod 2 cylinder Mariner/Yamaha

  1. #11
    modifiedoutboard OUTBOARDER's Avatar
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    Default nothing new under the sun

    Quote Originally Posted by Fast Fred View Post
    the exhaust on the 60DES was separate from each other, twin cow bell. held all 750cc records.at about 5500rpms about 40hp slams into the power band.
    Yamaha SUPERJET 701 TWIN
    comes stock with individual tuners similar to the 60 twin, makes 73 hp , with twin 38mm carbs and several other similarities to the 45.
    Difference is in the late nineties RD Performance figured out a exhaust the worked from 3,500 rpms up. I was fortunate enough to talk to the engine guru there several times. He said they filled up a 40ft trailer with test pipes. They end result was a pipe that bumped a stock 73 hp Yamaha up to 100hp. In 1999 and 2,000 RD dominated every heat of the Worlds with that pipe. On a ported Yamaha they sell the pipe in a kit and gaurentee 140 hp from 7,400 to 7,800 along with arm wrenching acceleration. They said they could make more power but the drivers want acceleration. I have one of the pipes never used it or RD race porting specs. Just running rec specs. Stock Super Jet Exhaust opens at 89 deg ATDC Transfers open at 120/118 deg ATDC .
    ANTHONY McCULLOCH
    modifiedoutboard@hotmail.com

    Some things never change!

    They Want it cheap..............

  2. #12
    Team Member 88workcar's Avatar
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    Got one on hand, I'm all ears.
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    Helping folks out around the globe.

  3. #13
    modifiedoutboard OUTBOARDER's Avatar
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    Default step 1

    Quote Originally Posted by 88workcar View Post
    Got one on hand, I'm all ears.
    Are these engines Available?
    How much for a beater to rebuild?
    How many rpms will these turn w/o flying apart?
    What is bore centers distance?
    What is rod/ratio?
    Can you take good pics of block inside and out?
    ANTHONY McCULLOCH
    modifiedoutboard@hotmail.com

    Some things never change!

    They Want it cheap..............

  4. #14
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    Quote Originally Posted by OUTBOARDER View Post
    Are these engines Available?
    How much for a beater to rebuild?
    How many rpms will these turn w/o flying apart?
    What is bore centers distance?
    What is rod/ratio?
    Can you take good pics of block inside and out?
    I can help you out a bit
    2 cylinders. 46.4 displacement. The bore width is 3.23" and the stroke length is 2.83".
    They will turn 8000
    Solid steel crank
    used complete motor $500.00
    You can still get new parts thru Yamaha....same basic motor as their commercial 55 hp.
    Wisco has pistons
    Boyensen has reeds
    Bone stock with no mods they turn 7000.

  5. #15
    49ci OMC, Alum flat sabine river killer's Avatar
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    that boy has a few of them from what he has told me

  6. #16
    modifiedoutboard OUTBOARDER's Avatar
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    Default pull the cylinder head

    Quote Originally Posted by Hounddog View Post
    I can help you out a bit
    2 cylinders. 46.4 displacement. The bore width is 3.23" and the stroke length is 2.83".
    They will turn 8000
    Solid steel crank
    used complete motor $500.00
    You can still get new parts thru Yamaha....same basic motor as their commercial 55 hp.
    Wisco has pistons
    Boyensen has reeds
    Bone stock with no mods they turn 7000.
    Sounds good so far, how far apart are cylinders ?
    Pull head lets look at it.
    ANTHONY McCULLOCH
    modifiedoutboard@hotmail.com

    Some things never change!

    They Want it cheap..............

  7. #17
    Team Member 88workcar's Avatar
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    Hounddog speak to me. What do I do?
    Helping folks out around the globe.

  8. #18
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    Quote Originally Posted by 88workcar View Post
    Hounddog speak to me. What do I do?
    I have a powerhead, it is up north in snow country, I can't get to it to take pictures to show.
    I suggest you post the pictures of your motor and see what suggestions are made. I think the key is getting small chamber heads made [to get about 170 psi], port the motor like a mod 90 yamaha including finger ports. Add plastic reeds. Leave the exhaust as is until you get to try it. The exhaust mod would be the final tune.

  9. #19
    modifiedoutboard OUTBOARDER's Avatar
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    Default send me two blocks

    Quote Originally Posted by Hounddog View Post
    I have a powerhead, it is up north in snow country, I can't get to it to take pictures to show.
    I suggest you post the pictures of your motor and see what suggestions are made. I think the key is getting small chamber heads made [to get about 170 psi], port the motor like a mod 90 yamaha including finger ports. Add plastic reeds. Leave the exhaust as is until you get to try it. The exhaust mod would be the final tune.
    send me two blocks , will port behind liners , set up head for your fuel , make bolt on out the mid pipe(with removable beer can silencer) , mod intake system to engine set up . I keep one short block for my project. can get 100hp @7,000 with over rev to 7,800 on 93 pump gas with reliability and longevity.
    ANTHONY McCULLOCH
    modifiedoutboard@hotmail.com

    Some things never change!

    They Want it cheap..............

  10. #20
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    Thumbs up

    Quote Originally Posted by OUTBOARDER View Post
    send me two blocks , will port behind liners , set up head for your fuel , make bolt on out the mid pipe(with removable beer can silencer) , mod intake system to engine set up . I keep one short block for my project. can get 100hp @7,000 with over rev to 7,800 on 93 pump gas with reliability and longevity.
    WOW!! 88 workcar....Take him up on that offer if you have 2 blocks. I would if I had two blocks!

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