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  1. #1
    Tony's Avatar
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    Unhappy Carbs full of crap!!

    Well I had time to strip my carbs down today and was rather surprised at what I found. The inlet screen has a few small particles in it, nothing to speak of really, but the rest of the assembly had alot of grit/sand/crap in it.

    Where did this come from? Did it come in with the oil? I checked and there's a inline filter in the oil line.

    What about the orifice just below the inlet screen, what is it's purpose? 2 of the 3 were completely blocked by crap and the other was getting close to full blockage.

    My adjustment screws were:

    low:
    M 1 3/8
    C 1 1/4
    P 1 3/8

    High:
    M 1 1/4
    C 1 1/2 (specs list 7/8 )
    P 1 5/8


    Jets were stock 67.5 and 110

    As some of you know I fried the top end due to a lean condition. Would it hurt to go one size larger and adjust with screws if needed?

    I'm also thinking about going with either some Boyseen or Carbon Tech reeds...with no other mods how much larger would I need to jet?


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Tough to say how debris got past the filters, but I would go with larger jets, how big??????? Maybe 2 sizes larger after reeds. Just a guess, since your settings were kinda close to needing bigger jets already.. I thought I read that 1 1/4 turns out should go up 1 jet size. Don't quote me.

  3. #3
    Tony's Avatar
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    Quote Originally Posted by xlint89 View Post
    Maybe 2 sizes larger after reeds. Just a guess, since your settings were kinda close to needing bigger jets already.. I thought I read that 1 1/4 turns out should go up 1 jet size. Don't quote me.
    Thanks for the reply xlint89. I didn't realize my settings were close to needing bigger jets already I just figured bigger would give me more adjustment room to help avoid my current lean condition.

    What about the orifice just below where the inlet screens/filters are? Any idea what that's for?

    Guess I need to do some more reading on carb tuneing and jetting.

  4. #4
    ph2ocraft's Avatar
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    With the clean carbs you shouldn't have a lean condition anymore (unless you still have a fuel restriction elsewhere) so the factory settings should be fine.
    Get her cleaned up and then check the mixture on your next ride(s).
    Can you post a photo of the orifice you're talking about?

  5. #5
    Tony's Avatar
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    Quote Originally Posted by ph2ocraft View Post
    Can you post a photo of the orifice you're talking about?
    Bottom right hand corner. Below inlet filter....between filter and lower right hand screw hole.

    Click image for larger version. 

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    Click image for larger version. 

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  6. #6
    PWCless for now Majumba's Avatar
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    According to the Mikuni Manual in the tech section it's a fuel return. But I'm not positive that's correct. Hard to tell which carb they are showing.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  7. #7
    Tony's Avatar
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    Thanks Majumba, that's exactally what it is. Since I have the stock triple pump all carbs were getting fuel but I'd think that with the returns blocked I'd have high fuel pressure. Does that sound right?

    ph2ocraft, The carbs will be spotless. Since I'm not sure that dirty carbs are the only thing that contributed to the lean condition I'm replaceing the whole fuel system...float, lines, tank vents, selector, pump, the whole nine yards.

    That brings me back to the question of jet size. If I stay stock will one size larger jet be too much? Oh never mind, who am I kidding, I going to go with some aftermarket reeds at the very least so I guess I'll buy a small assortment of jets.

    And one last question. Do you guys rejet with the carbs installed? I've never thought about it and since my ski is currently in pieces I can't tell if it's doable or not.

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    The carbs need to be removed from the boat to rejet.

  9. #9
    cheatin' piston popper addicted's Avatar
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    that crap is probably from unstabilized gas degrading in the carb over the winter. Make sure you completey dissect those things and clean them. take a dentist's pick and scrape anything that looks like dried up varnish. you need to scrape the crap off. carb cleaner won't remove it! if you don't, the fresh gas running through there will loosen the deposits eventually and you will melt some more yummy pistons. pay attention to the tube that connects the filter to the needle and seat, as well as the horshshoe thing that holds the N&S in.

    I would cautiously stick with the stock jets, but monitor the engine closely. It might be right, it might be way off. See this thread, http://www.greenhulk.net/forums/showthread.php?t=30185

  10. #10
    Tony's Avatar
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    Quote Originally Posted by addicted View Post
    take a dentist's pick and scrape anything that looks like dried up varnish. you need to scrape the crap off.
    Already started with a mechanics scribe.

    Quote Originally Posted by addicted View Post
    you will melt some more yummy pistons.


    Quote Originally Posted by addicted View Post
    as well as the horshshoe thing that holds the N&S in.
    Not sure I know what you mean here, can you explain a litle farther?


    Quote Originally Posted by addicted View Post

    I would cautiously stick with the stock jets, but monitor the engine closely.
    I forgot to mention I'm going premix....does this still hold true about the stock jets, and what about with aftermarket reeds?

    Quote Originally Posted by addicted View Post
    Thanks, I've been following that thread.

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