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  1. #1

    To JET or not to JET

    Been reading for a while. Seems like a great bunch of guys. I would like some advice to jet or not to jet.

    2001 gp1200r
    aftermarket F/A
    just converted to p/mix
    o-plate and chip
    fuel flap removed (broke anyway)
    wave eater clips
    still deciding if I wanna run yamalube or not (2r)
    fresh motor (crank, pistons, rings all seals etc...)
    stock choke

    i already have the exhaust removed so is it worth the 120 plus ship to rejet the carbs and remove the acc pump or can I get away with adjusting high/low needles and leaving acc pump? (already removed tamper proof caps)

    im deathly afraid of the mid range lean failure I have herd so much about. Will going premix and adjusting stock high low needles resolve that lean issue or is rejetting the only option?


  2. #2
    powerstroke specialist mikegp's Avatar
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    I will have them rejet. it will definitely run better will star better and it will be safe for the engine, and get that acc pump out.

  3. #3
    I was leaning that way from what I have read. Now I have another question. I have found individual jets, N&S, and other parts from Atlantic Jet Sports. Why is the island racing kit so expensive? I understand it comes with an acc pump block off kit but 120 bucks? The jets are only 4 bucks and 15 for N&S. what else would I need?

    Thanks, John

  4. #4
    Never mind. When I do math correctly it comes out pretty close. Dead thread

  5. #5

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    When you remove the stock flame arrestor and reinstall aftermarket free flow arrestors, the vacume (signal) that helps to draw the proper amount of fuel into the carbs change. For this reason, you have to rejet, or else, you will have that lean condition that you are afraid of.

    You do not have to REMOVE the accellerator pump. You can DISABLE the accellerator pump by removing the cam so that when you pull the throttle, it does not squirt any fuel into the carbs. By leaving the pump in place, it can still act as a primer. What you would have to do is reach under the pipe to press the primer (pump) button. This is how my 1200 has been set up for years. I never had to install an aftermarket primer system, just used what Yamaha originally set up.

    What I am saying is that all you need are the jets, needle and seats, and springs.

  6. #6
    powerstroke specialist mikegp's Avatar
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    i don't have primer kit or acc pump on mine , didn't have any problem starting the first time. i use this setup below.

    1200R Aftermarket F/A's chokes intact
    ••110 Pilot jets, 1 turn out on low speed adjusters
    •120 main jets, 1-1/2 turn out on high speed adjusters
    •1.5 Needle and Seat, 95 gram spring (Dull Silver) 42-45 avg. pop-off pressure.

  7. #7
    powerstroke specialist mikegp's Avatar
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    or you can do this one.

    1200R After Market F/A's chokes removed.
    ••110 Pilot jets, 1 turn out on low speed adjusters.
    •125 Main jets 1-1/2 turn out on high speed adjusters
    •1.5 Needle and Seat, 95 gram spring (Dull Silver) 42-45 avg. pop-off pressure.

  8. #8
    Does anyone know the part numbers or even a link to the ones I need? I have called island racing. Left VM and its been a few days. I've given up and won't be ordering from them. From my understanding the carb we (gp1200r) have is a 44mm I body mikuni? Most the sites i see talk about a round or square body.

    I am rather mechanically inclined but this is my first pwc, first triple cyl, and most of my skills were acquired on 4strokes and single carb 2 stroke quads. Just don't want to order the wrong parts.

    Thank you, John

  9. #9

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    moving thread..
    Last edited by kwkyamaha; 07-10-2013 at 11:03 PM.

  10. #10
    powerstroke specialist mikegp's Avatar
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    Quote Originally Posted by BabyBear View Post
    Does anyone know the part numbers or even a link to the ones I need? I have called island racing. Left VM and its been a few days. I've given up and won't be ordering from them. From my understanding the carb we (gp1200r) have is a 44mm I body mikuni? Most the sites i see talk about a round or square body.

    I am rather mechanically inclined but this is my first pwc, first triple cyl, and most of my skills were acquired on 4strokes and single carb 2 stroke quads. Just don't want to order the wrong parts.

    Thank you, John
    you need to call riva and ask for pete. you give him the jet numbers . get T handlers for both low and high

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