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  1. #1

    Join Date
    Feb 2014
    kemah tx

    2000 gp 1200 carb help

    i recently picked up a pair of 2000 gp 1200s and im in the process of cleaning the the carbs, draining the gas, getting them cleaned and ready for the season. i have rebuild carbs for a xlt 1200 for a couple for friends so im some what familiar with the carbs. on the fist ski the carbs, they looked like all the other carbs i have seen. on the second ski, the accelerator pump had hoses go to all three carbs, which is not like the first ski or on all the other skis i have done before, where the accelerator pump had hoses go to the first and last carb skipping the middle. also the second ski has the resonator in a million pieces, im guessing from a back fire. my question is is there a big difference in the two carbs? is one better than the other? any and all info on these carbs will be helpful. im planning to put a free flow exhaust on the ski, oil block off, d plate and wave eaters, other than that they will be stock for now. is there any tuning i need to do to them?

  2. #2
    The carbs are all the same (except for option differences like you've found) on the 1200 PV (66V) motors, Mikuni 44i's that are specific to yamaha. I have no idea why the 3 accelerator pump inlets went down to 2 in later 66V models. I think the accelerator pump is different too if you compare the pump on the 3 hose vs 2 hose version. Anyway the carb internals are the same (same rebuild kits, parts, jets, mix screws...etc). You may also find some carb to engine mounting differences too. The older engines have a spongy gasket that goes between the carb rack and the engine and newer ones have a spacer piece and 2 paper gaskets. Dunno why that change was made either. There's sticky's for tuning/jetting/modding...etc in the yamaha 2 stroke section here. Do a google search for "mikuni super bn owners manual" and there's a lot of good tuning info there and it explains how each portion of the carb works. A tachometer is useful for engine tuning too (one that updates quickly and has a number readout). The bargraph tach on the dash isn't particularly useful for tuning.

    No idea what you're referring to as the resonator. If you're referring to a big cast exhaust pipe (or any metal pipe really) that blew up, that's probably pretty bad. I'd guess you're referring to the catalytic converter though. Those seem to blow up regularly. So yeah get rid of that on both (get all the pieces out of the exhaust), d-plate in its place, and wave eaters. Most people here say any exhaust changes other than the stock monsterous exhaust system robs engine performance. That'll be your decision I guess.

    Same w/ the oil pump removal. I chose to stay w/ the pump (tested it, made sure it was clean inside), but replaced all the oil lines w/ 1/8" ID and 1/4" ID tygon and used oetiker clamps on all connections. I also replaced the check valves as those were questionable. Whether you go premix or not is up to you. I wouldn't like the slight extra hassle of premix, extra oil consumption, and the extra idle smoke, so I stayed w/ the oil pump. But if you premix correctly and accurately, you should never have an engine failure due to lack of lube coming into the crankcase. You also free up a tiny bit of engine power not turning the pump. Neither choice is clearly right or wrong I don't think, whichever suits you best is the correct choice.

    Good luck!

  3. #3

    Join Date
    Feb 2014
    kemah tx
    thanks awh for the info. the resonator in referring to is the black plastic "box" coming off the water box, under the battery box.

  4. #4
    Prism's Avatar
    Join Date
    May 2007
    "New" Jersey
    Well I'll be! Your the first one to ever ask about do you say...GP1200R carbs. I don't think they're rebuildable... Nah just kidding! This gets asked about three times a week this time of year. Here is the best way to set up your carbs. It's found in the sticky part of the FAQ/how to page.

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