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  1. #1

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    gp1200r carb adjustment need help!!!!!

    ok so i adjusted my highs to 1 turn and my lows to 2 turns . It ran ok at full speed and was bogging down out of the hull so i re-adjusted the highs to 3/4 and lows to 2 and a half turns. Rode it again and the ski was perfect at top speed and better out of the hull but still every now and then it was bogging out of the hull. Do you think it is running to rich on the low speeds now and that i need to re-adjust to 2 and 1/4 turns or should i go 2 and 3/4 turns on the low speeds ? just need some advice because it is a bitch to get to the carbs and i do not have the t-handle adjusters


  2. #2
    mudslanger's Avatar
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    T handles and flame arrestors are the way to go.

  3. #3
    Quote Originally Posted by mudslanger View Post
    T handles and flame arrestors are the way to go.

    Hey that was Great advice Sorry Mudslanger, but it begged that response...it's all good brother!

    OP, we're gonna need more info on what mods you currently have and weather or not when you say "out of the hole", you're talking about from a stop or throttle-chop while coasting from say a high speed pass(?) The answers to some of those questions could reveal more than carb adjustments or even jetting changes... . Please provide more info.

    ....and oh yeah, Mud's rite, T handles indeed, and while you're at it, a stinger or TT will help too

  4. #4
    jdakrt's Avatar
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    if its a stock boat, your too rich down low. IMO its 1-1/8 low and 1-1/4 to 1-1/2 high. But as the others stated you need to share more info. have you done a plug chop at WOT? Your supposed to tune in this order-idle adjuster, low adjuster, low speed jets, pop off, hi speed jets, then hi speed adjusters.

  5. #5

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    ok from what mods i know that have been done is riva heads d plate a freeflow exaust ive blocked off the oil injection and running pre-mix 40-1 not sure on the impeller but its cavitating at standstill when i accelerate so i will be replacing the impeller and wear ring if needed an r and d ride plate and pump nozzle and i think that is about it for the mods which i am aware of . i tried running the ski with 1 and 1/4 turns on the high speed jets but it just does not want to run properly at all and tried it with 2 turns of the low speeds and the ski from taking off from start would only go if i kept pumping the throttle a million times like i was using the accelerator pump to dump more fuel in to take off so im sort of thinking i might need to re-jet the low speed jets anyone got anymore advice for me ?

  6. #6

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    oh and what is a stinger and tt ?

  7. #7
    jdakrt's Avatar
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    somethings not right. There is no reason to be over 2 turns out on any adjuster. Check the jets, fuel filters, diaphrams. You could also be pulling in air somwhere other than the carbs. That transition pulls quite a bit of vacuum on the cases etc.

  8. #8
    ...check to see if you've got aftermarket air filter/flame arrestor, and/or wether your stock air intake's been modified. And also look at your plugs to see if they are white and/or black. The fuel/air mixture is what your troubleshooting for right now. I think that would be the first/easiest thing to trouble shoot. Other questions:

    1. Check compression?
    2. Check for trash or quality of fuel?
    3. When you test your settings, only test low/high one set at a time. Adjust lows; then go out and test. Adjust highs; then test. But not both at the same time.
    4. Does this occur only when the engine is cold?
    5. If it's from a stop, are you sure it's not simply the lag created by waterbox blow-out?
    6. If it's from coasting, it's probably running lean down low/low speed jets or accelerator pump not working. Can you use an ohm meter to check?

    Do all that then report back your findings....

  9. #9

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    ok so airbox is stock,checked the compressions 1=131psi 2=129psi 3=125psi,checked the spark plugs 1 and 2 were black and 3 was a light brown fuel is fresh and clear of water and is 98 octance left high speed jets at 3/4turn and while re adjusting low speed jets noticed number 3 was 2and 1/4 turns while carb 1 and 2 were 2and 3/4turns. Re adjusted to 2 turns on the low speed jets and left the highs at 1 and 1/4 turn and tested. Ski from standing start and opening up to full throttle would just bog down but it would take off better when i would use the choke so its definantly not getting enough fuel so im wondering if i need to change the jets in the low speeds because i never had a problem when i used to have the oil pump conected so im guessing because im running premix now the fuel/oil mis is too thick to pass through the low speed jets and that is why i have to wind out my low speed jets too more that 2 turns for the ski to actually take off ok

  10. #10
    ...good job! Sounds like you might have identified the problem. Since now you're using pre-mix, what's your pre-mix ratio? Remember two things:

    1. Fuel/air ratio: As the temp drops, you will have a tendancy to run lean. You can compensate to 'some' extent by going to say 50:1 if you're using a synthetic/high quality premix designed for such ratio.

    2. Fuel/oil ratio: The black plugs are definately not a good sign and 'may' be your premix ratio/type of oil is not correct. What are you running?

    One thing I didn't mention was a overich fuel/air ratio symptom. If after a cold engine start-up, ride it, then you park the ski for say 15 min., then when you go to start it again without the need for choke, you're too rich at your low speed curcuit. (That will give you a 'bog' condition.) However, you mentioned you pulled the choke while accelerating and it stopped surging and regained it's take off, indicating lean-ness. Therefore, I think we've identified the problem. So, check the pre-mix then report back... .

    BTW, you said you have aftermarket heads...that compression is a bit low....are they 150 psi heads? Did you do the test correctly? Fresh battery? How many hours on engine? 98 octane for that compression may make it run sluggish. You don't need that high octane if you've only got 130+/- psi.

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