Too lean?????

Discussion in 'Sportster Models' started by Lang, May 31, 2011.

  1. Lang

    Lang Member

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    hi everyone, just wanted to know if i have done any damage by changing to a leaner pilot jet like the joe minton article in american iron suggested. i tried it and the bike runs good but i have a few coughs here and there. i had like 4 in one day. it still seems a little lean to me but the plugs look good, but i can feel that it just isn't as smooth as it could be if i'm riding around 1/8 throttle but smooths right out at 1/4 throttle. am i running lean enough to do any damage? thanks

    Lang

    also i running the richer needle from a 1200 in it as well with about 3 to 3 1/2 turns out with the air/fuel mixture screw. i have a 1250 kit with andrews n4 cams, stock heads, se II slipons, arlen ness big sucker II a/c, twin tec 1005 ignition module. thanks again
     
    Last edited by a moderator: May 31, 2011
  2. BUBBIE

    BUBBIE Well-Known Member

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    What size Jets are you using NOW with it running BAD?.... NO damage probably,,,,,,Coughing doesn't do the damage HEAT from LEAN ruins the engine..

    Sounds like the low speed jet is TOO small... Your IDLE screw should end up at 2.5 turns out (not 3.5)... you need to change the Jet... The RIGHT idle Jet will adjust to 2.5 turns out OR close on the RIGHT idle screw...

    IF it is a .043, go 45, if it is a 45 go 46...47 ****** the 048 may be Bigger than you probably need...

    WHAT is the size of the Main Jet? 170 180 185 190?????

    GO .005 bigger and that should be good there also..

    signed....BUBBIE
     
  3. Lang

    Lang Member

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    im running a 42 pilot and a 180 main with a needle from a 1200 (its supposed to be a richer needle).... plugs still look ok, not too lean looking.... im thinking the bike would run alot worse and cough and sputter alot more if it was so lean as to cause any damage. right?
     
  4. BUBBIE

    BUBBIE Well-Known Member

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    YES, I don't see it being damaged the way you described it.. NO damage,,,,

    The Lean Mix causing HEAT will destroy a motor and Too much advance on the spark and or using Low octane fuel will do a good amount of damage and Quickly..
    I'd change out the low speed to a 44 and try that .. The 42 is small and the setting of the idle screw dictate that to me.. Try it.. then we'll Both Know

    One trick I use on My 06 sport R is taking out the carb Phillips screws(4) and replace them with (5/8" long) allen heads.. This makes it easier for me to take off the carb bowl, WHILE on the bike to change out the jets..

    I always seem to strip out a phillips.. careful you don't Over tighten the allen screws, and make sure the Arm and rubber is in the right spot when you re-attach the bowl..

    IF the Old sportster Needle is the right one,,, it has a Slender tapper to it and does about the same thing as putting 2 #4 copper washers under the stock needle.... Gets more fuel quicker to the High end..

    signed....BUBBIE
     
  5. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The 42 slow jet would be the stock size and is a wee bit on the lean side with the stock air box and air cleaner
    coughing back through the carb is usually associated with a lean slow jet
    and as bubbie said 2 1/2 turns out is an indicator that the slow jet is near right
    44 is a good place to start and should reduce the cough back through the carb and sharpen things up a wee bit at low speeds

    Brian
     
  6. Lang

    Lang Member

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    as far as heat goes the temp on my oil gauge seems normal to what it always was even when i had a 45 jet in there. i cant get a 44 at the dealer correct? who sells them? like i said even when cruising at 1/8 throttle the bike wasn't coughing or anything it only did it when i would let off the throttle for a second then just give it a slight turn. i wish i could stop worrying about doing damage to the bike and just enjoy riding... thanks:wall
     
  7. Hoople

    Hoople Account Removed

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    By chance would you know which month the article was in. I have not read it.
     
  8. Lang

    Lang Member

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    i think the article was in last months issue, sorry i dont remember the month. i dont have it in front of me right now but i'll look. still afraid i did damage by running it like that. thanks
     
  9. Hoople

    Hoople Account Removed

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    I would like to read the article just to understand the purpose behind changing the mixture to start with.

    You said it was suggested. It was suggested for what reason, What were you originally trying to correct.
     
  10. BUBBIE

    BUBBIE Well-Known Member

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    STOP WORRYING,,, You DON"T have the bike that FAR OUT to do damage YET....

    Try the 45,,,,TRYING wont hurt a thing.. IF your idle setting is LESS than 2.5 turns it is TOO BIG and the .044 is needed....

    Ask HD parts man behind the counter IF they sell separate jets,,,, usually a box full to choose from..
    IF NOT find an Indy shop, as they usually DO..

    signed....BUBBIE