Sportster Rejet Carb Issues

Discussion in 'Sportster Models' started by JDPEagle, Jan 3, 2010.

  1. JDPEagle

    JDPEagle Active Member

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    Need some major assistance on this one. I installed some new Rush slipons and a DynoJet kit on my wife's 2003 883C Sporty over the holiday (haven't gotten the SE AC on yet). After following the DynoJet instructions to a "T." The bike will not get much above idle before "coughing" and stalling. The accelerator pump appears to work, and the bike roars with determination when "reving"; however, a gradual roll on the throttle results in a "fluttering" slide (I call it coughing) and a stall at varying RPMs (usually when trying to sustain a high RPM).

    I have tried so many things (mixture screw adjustment, installed 45 low jet, installed both 170/180 main jets, inspection of the float and float needle, inspection of upper diaphragm and seal). I did drill out the slide per the kit instructions. I have systematically gone back through and replaced stock components (where able), and the issue persists.

    Any ideas or assistance... Glider... :bigsmiley25:
     
  2. maine-e-axe

    maine-e-axe Junior Member

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    Maybe the float is to low, how much gas is in the bowl when you take the bowl off? just a thought.
     
  3. JDPEagle

    JDPEagle Active Member

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    Before going back into the bowl with each new adjustment/troubleshooting endeavor, I have drained a substantial amount of fuel from the bowl through the drain screw.
     
  4. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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  5. JDPEagle

    JDPEagle Active Member

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    I only drilled out the slide vent hole (per the instructions) and NOT the emulsion tube.

    I did see this. Unfortunately it was AFTER my original install. I can certainly understand the objection to drilling out the slide; however, I'm not sure that doing so would result in my symptoms... maybe :newsmile070:
     
  6. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Unfortunately, drill is not precise enough to leave a mirror finish; those small irregularities can bind the needle slide surface and cause enough turbulence to affect the airflow & fuel mixture.
     
  7. BUBBIE

    BUBBIE Well-Known Member Contributor

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    BUBBIE HERE,,,,, I don't like the part about drilling out the slide(my preference)..... FLUTTER is very possible after doing the larger opening and a lot of times a lighter spring is used NO GOOD IMO

    almost sounds like the jet is missing the emulsion tube that fits above it?

    are you sure the push-rod is in the accelerator and SQUIRTING A full amount when you twist on the throttle all the way???

    I have ALWAYS gotten BETTER results when using the stock carb and only changing out the slide needle for the OLDER 1200 sport one....(change jetting corrected accordingly) using SPARK PLUGS colors as part of the determining factor...

    I do smooth OFF the sharp edge from the slide bottom (facing you)::: that allows air to move with less resistance getting into the throat of venturi.

    hope glider comes along with an answer or suggestion..... REALLY GOOD TO SEE HIM BACK....


    signed....BUBBIE
     
  8. JDPEagle

    JDPEagle Active Member

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    Keep the ideas coming! I tried a few more things tonight... but I think they only led to more confusion.

    I went to the dealership today and bought a new stock slide and diaphragm (just to be able to return the carb to bare stock as it was [and ran] before). To my utter shock, the bike is still having the same problem with the carb back to stock! I have checked the diaphragm (and it's seating) thoroughly.

    I have noticed one new thing, however. Wen the bike begins to stumble (at the higher RPM), covering the intake with my hand induces a recovery and a return the elevated RPM. Therefore, I know that the bike is running lean at that point (adding full enricher accomplishes the same thing).

    Several checks of the fuel valve vacuum system (hose and valve), carb float and float needle, and fuel delivery line returned satisfactory results.

    Every test I can think of indicates a perfectly functioning fuel delivery system (other than the run-up test).

    This might be a stupid question, but would the absence of an air filter element cause this behavior? I have not tried putting the stock A/C back on, but the problems did persist with the SE A/C.

    I think I'm going loony! :bigsmiley30:
     
  9. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    The drilled out tube is likely the problem, especially if you replaced the stock diaphram, slide and needle...you should of course put 2 #4 stainless washers under the needle (may richen it that extra bit and helped my sporty), which had a dead spot off idle. Do check that the accelerator pump is squeezing a full measure of fuel and make sure when you look at the slide while slowly opening the throttle, it moves smoothly. Only other thing is to order a new non-drilled tube assembly or even another used carburetor to rebulid as last resort. Also, you really do have to check that fuel level in the float bowl, either using a clear tube installed tightly in the drain hole "J" shaped up,to see if fuel goes to within 1/8 to 1/4" of the top seam (preferred fuel level measurement if on bike) OR if the carb is off check the float drop/angle as specified in manual.
     
  10. JDPEagle

    JDPEagle Active Member

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    I didn't drill out a "tube." I only drilled out the slide (was replaced with the stock diaphragm [all one part]). So the entire carb is back to stock.

    I checked the float drop/angle and it is right on with the shop manual. I am going to try this clear tubing as I have a very strong suspicion now that I am sitting here and thinking about it. My suspicion is with the vacuum fuel petcock and the bowl "emptying" under the high throttle/RPM.

    I will let you know what I find when I try this.

    Thanks!