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  1. #1

    Carb issues 98xpl

    freshly rebuilt carbs on a freshly rebuilt motor.
    Plugs are wet and obviously rich. Bogs when accelerating and will sometimes stall. Starts fine.
    if i am easy on the throttle and gradual it will try to go until I go past half or even 3/4 throttle. At which point it rips. This part is consistent.
    Choke will kill it at all throttle stages which further indicates that it's rich.
    I tried screwing in the L screws visible from the top 1/8 at a time but I did not get any changes at all.
    reading through the notes on the carb tuning sticky it seems to me that my next step should be to take them off and check pop off pressure? carb rebuild was done by a professional who is currently on vacay, and did not get a chance to tune them before leaving since motor was not yet done.
    Thx for all input as usual!


  2. #2
    Waterluvr's Avatar
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    Pressure testing will show you what went wrong, be sure to check the seat o-ring with a low pressure test and pop off with a regulated air source.

  3. #3
    Pacer's Avatar
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    Sounds like your accelerator pump isn't working. You should be able to hear it spray fuel when you squeeze the throttle without the engine running. Pull the Flame arreastor off far enough for you to get a finger into the carb opening. feel around, and there is a small brass nozzle about an inch long in the throat of the carb. with your finger on the inside of the nozzle, squeeze the throttle. If you don't get fuel spraying out of the nozzle, the accelerator pump isn't working.

    If its stock, and nothing has been changed I doubt its rich.

  4. #4
    The accelerator pumps were removed and jets changed during the rebuild.

  5. #5
    I have no reason to suspect bad work in my opinion, always did good work for me in the past - hope the work done is correct - so I m in no rush to open them up, I guess what I would like to do first is know if I can tune them at all without taking them off?

  6. #6
    Pacer's Avatar
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    What size low and main jets were installed? what other mods does the ski have? You can adjust the idle mixture by turning the T handle screws on top of the carbs. I have a 99 XPL with the accelerator pumps removed. I'm running a 90 low speed jet and 167 high speed jet. It jumps out of the hole.

  7. #7
    I don't know what was installed, didn't ask even though I should have... He gets back next week sometime so maybe it's easier to wait, could be wasting time...
    I ll just ride it at wot for now

  8. #8
    Pacer's Avatar
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    turn the T handle screws on the tops of the carbs. First, turn them both all the way in to see where they are set at. Then turn them out to about 1/4 more than they were set. See if that helps or hurts or makes no change. Adjust them again, and see if that helps. Do that either until the boat runs like it should, or you have them turned all the way down, or passed 2 turns out. If it gets better one way, then you know if you are lean or rich.

    I set one up like this for a guy using the stock airbox. The boat would jump out of the hole with the plastic air horns in the waterbox, but would bogg without them. They are finicky without the accelerator pumps.

  9. #9
    I have flame arrestors on... got it started yesterday, new plugs - I had a small electrical issue with the VTS so I had to put a new harness in, thankfully the mpem was not fried.

    Anyway, got it started and runs fine. Starts on the dime. The T screws on top are 3/4 turn out and it seems to run fine on the hose. Responsive to the throttle. No hesitation. Will drive to the water later this week and test in water.

  10. #10
    Put it in the water today, left on the trailer. Ran them at 3/4 turn out for 2-4 minutes. Idles at about 1200 and pushing the throttle slowly will get me up to 3500 rpm and it will sit there until I get the throttle past 3/4 that's when it shoots up to 7000 rpm and runs great.
    Went all the way to two turns out, and then kept turning them in 1/4 turn - runs about the same through the entire range even though it will idle slightly higher the more i turn it in. Between 3/4 and 0 it has a very hard time starting.
    applying instant throttle of at least 50% will always stall it, regardless of L screw position, even though I thought it was more obvious the leaner I got. I have to ease it in and then it will top out at 3500 -4000 before going to 7000 as I said above.
    I did add oil injection so maybe that is my issue, even though I think the notch is in the right place but I can look at it if you think that may cause it.
    Here are the plugs after the first 4 minutes at 3/4.
    Click image for larger version. 

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    Last edited by dcurbet; 07-15-2015 at 10:51 PM.

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