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  1. #1

    Opinion on sbn's SBT input

    THE CRANK IS NOT THE PROBLEM! the carb is the problem on the #1 cylinder. The 750 carbs are very touchy and when they get old this is the problem every one runs into. 1st off the 750 fuel pump is borderline on pumping the correct amount of fuel to a good set of carbs, when those 750 mikuni carbs start getting old the high speed path in the body swells up and starves the cylinder on fuel at high speed. I bet this guy could ride the ski for the next 10 years at low to mid throttle and never burn the piston but run it wide open for 15 seconds and BAM! hole in the piston. IF the pto burned then its a crank out of phaze but not the mag cylinder. The solution is re-build the engine and install a set of 780 carbs and 780 fuel pump and all of your problems will go away. Your 780 carbs will face a different direction, fuel rail to the out side of the engine, this was to solve a known lean condition going into left hand turns, When converting to 780 carbs you will need to get a throttle cable for a 780 model and choke cable because they come in at the back of the engine and hook up to the carbs instead of the front. LEAVE the 780 jetting alone use it like it is.
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    Anyone experience the carbs swelling?

    http://pwctoday.com/f17/slt-750-prob...-new-post.html


  2. #2
    seaobin's Avatar
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    Yes, I hit a wave the wrong way one time and the mag carb swelled up like a grapefruit. A few aspirin a day and kept it elevated and after a few weeks, I was able to ride again


    Oh wait, that was my right knee.

  3. #3
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Shouldn't this be in the Anytime BS thread?

  4. #4
    Moderator beerdart's Avatar
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    Quote Originally Posted by starflight View Post
    Shouldn't this be in the Anytime BS thread?

  5. #5
    1FASTXC's Avatar
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    I find that very hard to believe. Unless he's talking about gunk building up in the passages, i don't see how it's possible. Never heard of it before.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    ...Your 780 carbs will face a different direction, fuel rail to the out side of the engine, this was to solve a known lean condition going into left hand turns,

    When converting to 780 carbs you will need to get a throttle cable for a 780 model and choke cable because they come in at the back of the engine and hook up to the carbs instead of the front.

    LEAVE the 780 jetting alone use it like it is...
    What about the idea of using 780 carbs with 780 jetting on a 750 motor?
    Is that reasonable?

  7. #7
    Pain is fear leaving your body.... rlovebk's Avatar
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    Some of my "parts are occasionally swollen, but my wife says SBT can't have them.

  8. #8
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by K447 View Post
    What about the idea of using 780 carbs with 780 jetting on a 750 motor?
    Is that reasonable?
    I don't know about that. The later 780s had considerably larger jets.

    As for the left lean condition, I think the single outlet pump was the bigger problem. Plenty of folks around here have upgraded the pump only, as well as other general maintenance, and have had good results without having to change carbs.
    I really like the part about the high speed circuit swelling closed on the old 750s sbn38s.

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by rlovebk View Post
    Some of my "parts are occasionally swollen, but my wife says SBT can't have them.




    I know what SBT means......

    I soaked my SBN 38's overnight in the carb cleaner.

    They swelled so much, they were 44's the next day.

  10. #10
    I'm feeling naturally aspirated today pirate33's Avatar
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    My head swells really big, happens most the time as most of you know

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