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  1. #1

    Join Date
    Jun 2010
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    LKN, NC
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    GP1200r carbs running to lean

    I have a 02 Gp1200r, havin problems with the carbs running to lean. I have checked all gas lines. bypassed the gas on/off handle and flaper gas tank. Idles great, 1/4 to 1/2 runs good for 2mins then bloggs down ( shut it down and plugs are very lite brown). Run full troile, ski runs great for 30 sec. and does the same thing. Have gone thru the carb many times. they look great inside

    Carb settins
    Main 135 3 turns out
    low 110 1 1/2 turns out
    n/s 1.5
    pop off presure 32psi (65 gram spring)

    Engine mods
    Miller heads (42.5 cc domes) 120psi on all
    M-16 carbon reeds
    Riva f/a
    pro tec stinger pipe ( just to adjust cabs) will put stock W/ d plate


    Thanks for any help. I have worked on the carbs for many hours. I think the carbs need more fuel then the stock system will give it and i am runnin out of gas in the carbs.


  2. #2
    XLTNoob
    Join Date
    Jul 2007
    Location
    Baytown, TX
    Posts
    400
    have you pressure tested the engine? could be the case leaking. IMO, with 135 mains and the mods you have - you should be running too rich, even at stock adjustment screw settings.

  3. #3
    WATER WOODY's Avatar
    Join Date
    Aug 2005
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    Minden, Nevada, United States
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    Welcome to the forum. If thats all the mods you have that are listed, your mains are way too big!

    110 pilots
    120 mains
    1.5 n/s
    95 gram spring

  4. #4

    Join Date
    Jun 2010
    Location
    LKN, NC
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    Quote Originally Posted by WATER WOODY View Post
    Welcome to the forum. If thats all the mods you have that are listed, your mains are way too big!

    110 pilots
    120 mains
    1.5 n/s
    95 gram spring
    thanks woody, i try those settin last last and blow it up.

    Is there a way to persure test the pults line to the carbs?

  5. #5
    Moderator OsideBill's Avatar
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    Mar 2006
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    Those settings have been proven to work over and over again. I might add that this includes removal of the accel pump and addition of F/A's. You might want to check your return for obstructions in the carb body.

  6. #6

    Join Date
    Jun 2008
    Location
    St Clair Shores, MI
    Posts
    258
    Quote Originally Posted by dirtyski View Post
    Is there a way to persure test the pults line to the carbs?
    If you're concerned with them, just replace them.

    I'd rather be too fat than too lean, until you get the rest of the issue ironed out I wouldn't jet it any lower. All the threads here said 115 pilots and 135 mains for my setup, I'm currently running 145 mains because I don't want to blow it up. It doesn't seem to load up at high RPMs, so I'm not thinking overfueling would cause your problems at all. I know I'm running too rich... but I did this intentionally, to be on the safe side to start with a fresh motor. And it doesn't seem to be causing the problem you're describing, so I don't think leaning your machine out is the fix for your problem right now. Although it's something to look at when you get it running right.

    Take a look at your pistons and see how rich / lean you're running. You can do this without removing the head if you buy a fiber optic scope for $100 or less. Plus it's a cool tool to have

    Pressure test your motor, as was already mentioned.

    Check your fuel filter. Or, just replace it. Also, pull the lines out of the tank, the whole assembly, and check all the lines. Clean the screen at the bottom. You can also remove the flapper at the bottom. I don't know if restricts flow, but on mine it was warped so I removed it anyway. If you do this, be more careful running at low fuel because fuel will slosh away from the pickups. I noticed that slightly before I got to low fuel ("warning" coming on the gauge) if I ran quick, then let off, then gunned it again, it hesitated... i'm assuming the fuel was sloshing away from the pickups, and my removing the trap door allowed it to drain away from the pickup faster. While you have the lines out of the tank, blow compressed air through them to make sure they're clear. Watch out, you'll send fuel squirting everywhere if you don't point the end of the line somewhere. And don't send high pressure air to your carbs, you can mess them up.

    Also, drill out the carb restrictors and put a 90 main jet in the return line, if you haven't already. If all 3 are starving for fuel, though, I doubt that's your problem.

  7. #7

    Join Date
    Jun 2010
    Location
    LKN, NC
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    I have already remove the accel pump, installed F/A, flapper in the gas tank. I put a new fuel filter in it last month. Going to get new fuel lines and test it.

    Hads anyone put a fuel pressure gauge on there ski?
    what sould the fuel pressure be at?

    Hey Bill, I want you do some work on my stock head. Hear you can get the compresstion up around 145psi with stock heads. Or do you know where i can get new domes for a Miller tsc head?

  8. #8

    Join Date
    Jun 2010
    Location
    LKN, NC
    Posts
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    I put all new fuel lines on
    I changed the carb settin
    120 PILOT
    145 main
    and the spark plugs are still white.

    How do you test the case for leaks?

  9. #9
    Check in the how to section or search for pressure testing

  10. #10

    Join Date
    Jun 2010
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    LKN, NC
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    Quote Originally Posted by mi11ertyme26 View Post
    Check in the how to section or search for pressure testing
    Going to order a pressure kit form lowell

    thanks

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