Dealer tech says needs rejet

Discussion in 'Sportster Models' started by ngjandm, Aug 27, 2009.

  1. ngjandm

    ngjandm Active Member

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    Some of you might remember helping me a couple months after I bought my first harley in May of 2008, you helped me through doing some of my first work. V+H SS slipons; stage-1 air flow and rejetting the carb myself.

    Anyway I had to get 2 new tires the other day, the front because it was worn with very little tread, and the rear because the tire with only 600 miles on it had a brand new roofing nail in it.

    The dealers tech said I needed a rejet of my carb. He said I may need to go 1-up on the main, some other things as well (non-technical and from what I can remember) shim something, maybe drill something or do something with the needle.

    My novice ears apparently was not able to hear whatever he was hearing. To recap, I rejetted from the stock, 175 main / 42 pilot to a 170/45. Personally I may notice it pop, once every 2 weeks. Going 1 up on the main is going back to the 175? or 165?

    They suggest as well $50 to put it under the dyno to get exactly what needs to be done. Based on the info I have provided, could it be running lean? and could another rejet fix this rather than doing all that "other" stuff?
     
  2. ngjandm

    ngjandm Active Member

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    That's what I figured they wanted to do all kinds of stuff that really doesn't need to be done. As I said I am no expert, but the bike sounds ok to me, as well, just based on everyone's input, it doesn't sound like a 45/170 with a stage-1 upgraded would make the bike run lean. That was my biggest worry, was that it was not running lean.

    Do I need to do anything with the idle maybe? As well I basically went from 45mpg to 35mpg after all the upgrades.
     
  3. glider

    glider Veteran Member

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    Hobbit is dead on the money about the DJ kit.

    DON"T drill the slide which is what the tech said to do. Under some conditions like cold temps and sudden throttle opening it can bog the engine down from being too lean because it opens too fast.

    The #45 should do it in the low speed but a #46 would be better to eliminate any more problems with popping. Very little over the #45 but usually it's just what's needed to get the job done.

    You can shim the needle in the slide like Hobbit said which brings in the fuel in the mid to upper range a bit sooner for more kick.

    This post will explain it a bit better.

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community

    Don't forget to adjust the idle mixture screw to the highest and steadiest idle, usually about 2 1/2 turns open.
     
  4. ngjandm

    ngjandm Active Member

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    Rich could mean why my gas mileage took the large hit, but I haven't done any thing with the mixture. I will review all the info here you all have provided, and do some homework as well and should be good to go. I'll let ya know how it turns out. thanks again.
     
  5. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    As Glider and Hobbit have eluded to...and the fact your fuel mileage went from 45 to 35 mpg sounds like you are running a little rich than lean...are both pipe exits coated with black soot like you are running rich?

    Just a little more evidence before minor tweaking with idle screw, and needle height may be all that is needed.
     
    Last edited: Aug 27, 2009
  6. ngjandm

    ngjandm Active Member

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    the back most pipe has a lot of soot, the front pipe does not. I assume then when its running good, there should be no soot, I just assumed soot came with the tailpipe territory. unfortunately I will not be able to rejet until I return from my business trip to Shanghai. too bad I can't bring my bike with me.

    I'll get a 46 for the main jet, should I just leave the pilot at 170? I have both a 165 and 175, though I will have to order the 46 main jet.

    of course i mixed up my jets again. 46 for the pilot, should I leave the main jet at 170.
     
    Last edited by a moderator: Sep 2, 2009
  7. glider

    glider Veteran Member

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    Quick and easy way of testing the main jet size.

    Run the bike through the gears into third gear and run third up to 60-70 MPH full throttle, then chop the throttle about 1/8 to 1/4 back and see if the bike either surges ahead or stumbles then recovers.

    If it surges ahead, your jetting is lean
    If it stumbles and recovers , your jetting is rich
    If it makes no difference, you're pretty close.
     
  8. ngjandm

    ngjandm Active Member

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    did this test, up to 70, releasing throttle seemed to make no difference. the more i ride it now, i can feel it sputter some times at throttling up to about 1/4. almost like its trying to burn too much gas, and sometimes what sounds like a pop, hesitates sometimes until the throttle is more open.
     
  9. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    You are just experimenting with what makes the bike feel best to you. If you have all the other jets, try the #46 pilot and the #175 main. Put a washer under the needle to get to the speed band quicker.

    Warm the bike up nicely, set the rpm about 1,200 and adjust the idle-air mixture screw until the rpm is at its peak, then back out the needle about another 1/8-1/4 turn. If you find that adjusting the needle makes NO difference, drop the pilot back to the #45 (but I doubt this will happen). Set the idle back to the normal range (about 1,000rpm). Run around for a week BEFORE changing anything more. Make sure any further changes are because they are necessary, not because you are being super sensitive.

    TQ
     
  10. glider

    glider Veteran Member

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    Raising the needle should overcome that sputter. It will bring in the fuel a bit earlier. It's probably the result of a lean transition between the fuel circuits as long as there are no intake leaks.