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  1. #1

    Gp1200r hesitation

    Hey all,

    ive read up on some of the possible causes for the symptoms Im having but wanted to see if there is an order that I should check these things before starting. The ski was just rebuilt and the carbs were thoroughly cleaned. I removed the accel pump, and did the drilled return mod. I also got riva f/as. The jet ski fires right up with no problem at all and runs well overall. Every now and then it has a slight hesitation going from idle to full throttle. Itís like a 1 second hesitation before it takes off. Itís top speed right now on gps is 61 mph. I was thinking of changing the plugs first. So my thoughts are plugs, carbs or power valves. I hear the power valve motor cycle when I start it and shut it off, but thought maybe they need adjustment. Am I right to start with plugs? Thanks! Itís a 2000 gp1200r

  2. #2
    jeffg426690's Avatar
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    If it's your plugs they will be clearly and visibly fouled, although fouled plugs won't cause the symptom you are describing.
    Hesitation = lean.
    Either the accel pump or low speed adjuster. If you rejetted as you should with fa's you won't have an accel pump. If you didn't rejet your asking for trouble with the fa's.
    Assuming you followed the Oside recipe and DID rejet, check your low speed adjuster on the carbs and open them up 1/8 to 1/4 turn and see what that does.

  3. #3
    Quote Originally Posted by jeffg426690 View Post
    If it's your plugs they will be clearly and visibly fouled, although fouled plugs won't cause the symptom you are describing.
    Hesitation = lean.
    Either the accel pump or low speed adjuster. If you rejetted as you should with fa's you won't have an accel pump. If you didn't rejet your asking for trouble with the fa's.
    Assuming you followed the Oside recipe and DID rejet, check your low speed adjuster on the carbs and open them up 1/8 to 1/4 turn and see what that does.

    yeah, I followed the recipe. Iíll try that out, thanks!

  4. #4
    I’ve fiddled with the low speed jets for countless hours, I can’t seem to get it right. Can’t tell if it’s too lean or too rich


  5. #5
    jeffg426690's Avatar
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    Quote Originally Posted by Jaugi View Post
    Iíve fiddled with the low speed jets for countless hours, I canít seem to get it right. Canít tell if itís too lean or too rich
    If you want it perfect:
    Get a tiny tach, install the tach and bring it to a ramp. Back it in the water, leave on the trailer (so you have a load on the motor, can't tune it out of water). With the e-box unbolted and swung up out of the way you can reach the lows w the carbs in place reaching under the stinger (not easy, but can be done).
    Start at one turn out. Adjust in small 1/8 turn increments (make changes to all three) and watch the tach. You're looking for the highest rpm where it stays the most even. Too low and it will start to waver up/down. Too high and rpm will drop.
    Once at an even rpm, adjust idle to about 1100 rpm. (It will idle higher than this out of the water w no load on it).

    This method is from Group K, strongly recommend reading their articles on carb settings. Bear in mind that depending on your location and ambient air temperature variants you may have to re-adjust for cooler air temps sometime in the year. To play it safe, you can find your best setting and bump them a bit higher (more open) to account for temp swings and not be on the border of too lean. It should be nice and snappy w no bog or hesitation.
    This is assuming you have good clean carbs and no other fuel issues.

  6. #6
    jeffg426690's Avatar
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    Also: in re-reading your post - are you certain that you're not confusing some cavitation for hesitation? Hesitation: hit throttle and no rpm change for few moments, Cavitation: hit throttle and have immediate rpm response but ski not responding in movement/holeshot (kinda like a burnout in a car, motor is revving, tires spinning, vehicle not moving much)

  7. #7
    Thanks, I just rebuilt the carbs again and I’m going to try this stuff again. How long do you wait between adjustments? and yes it isn’t cavitation. The jet ski doesn’t rev up right away

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