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2001 gp1200r mods

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  • 2001 gp1200r mods

    I have a 2001 yamaha gp1200r that is only making 59mph on gps and i want more power.
    My current mods are -

    R&D - ride plate, intake grate, jet pump




    Im thinking about buying a power filter kit and a free flow exhaust. Would i need to rejet for that and what jets would be good? Ive also been reading about holeshot kits but i cannot find one that is available.


  • #2
    Welcome aboard. 60 for a stock ski is about average. Before you start going crazy check your compression, rebuild the carbs to Oside Bills specs, install Waveater clips, a D plate, PROK flame arrestors, remove the oil tank to save weight grind the ride plate to 5* make sure impeller is within spec at wear ring and drill the wind screen and storage bucket for more air.

    Read all the 2 stroke stickies… it’ll take time, but you’ll learn A LOT!! Knowledge is power. While you’re rebuilding the carbs remove the reeds and put in some CF ones. WFO has a bunch of parts and will also answer your questions. He’s helped us with our 1200R.
    Attached Files


    • #3
      compression is good on all three cylinders, carbs have been rebuilt with mikuni parts, d plate is installed, impeller is not rubbing on wear ring, reeds have also been replaced


      • #4
        What is your actual compression?
        Did you check your impeller clearance with a feeler gauge?

        The Oside Bill jetting specs really make for a more efficient engine that is less prone to lean conditions causing failure.

        The drilled return mod is a must… as the factory return is tiny. Ours was actually completely blocked with junk. Our pump bodies were also corroded and had to be sanded and trued.

        Also install adjustable mixture screws… this way you can dial in each cylinder.


        • #5
          The other thing I forgot to mention was the importance of checking the popoff.


          • #6
            Compression is 120 across
            what is the drilled return mod?


            • #8
              I've got a head that I milled for 140psi. Just right for 91-93 octane fuel. That would be a great mod ALONG with o'side Bill's carb recipe.


              • #9
                That head would be a nice upgrade.
                Hope we didn't scare you away- these older machines require some patience and skill, as you can't simply install parts and go. Some tuning is required.


                • #10
                  Jonesy has given you great info and solid advice on reading the stickies in the 2-stroke how-to section here.
                  Some of the mods are for reliability and some for performance or both. All worth looking into to make your machine reliable and fun.
                  I would add the following:
                  First, when you say more power do you mean higher top‐end speed or more grunt getting there? Two different things, although a lot of the mods apply to both. Adding grunt makes the ski a whole lot more fun all around and can be a lil' easier than chasing top mph which can take a lot of patience and trial/error for your particiular ski.
                  Great recreational mods:
                  Make sure you don't have cavitation (clearance between impeller and wear ring) then seal your pump w a seal kit and 3M 4200. This would be one of the first things I would look into.
                  Solas Concord 13/19 impeller.
                  Oside carb mod along w return mod while there. And yes, if you change the air intake you MUST rejet to Oside specs.
                  Mill the head to raise compression (20thou off is safe and gives a nice bump in compression while remaining reliable).
                  Holeshot mod (decent amount of work and only affects holeshot, but is noticeable difference).
                  Stepped sponson mod.
                  1200 grate unless you ride in really flat water, if so 800 grate will give lil' more top end but sucks in chop.

                  Have fun and enjoy the ski, you'll learn a lot with some reading and some light wrenching. Everything you want to know about the gpr is in the how-to's, learn from the gurus who have already done the homework and taken the valued time to share the knowledge.
                  'Nothing is fool-proof to a highly talented fool'