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Looking to rejet

Discussion in 'Motorcycle Tech Talk' started by pas, Apr 18, 2013.

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  1. pas

    pas New Member

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    I have 1993 evo 80" motor with tear drop S&S air cleaner with K&N air filter and drag pipes. bike is running lean. Right now has 165 main and 42 pilot N72 needle. Looking for jet suggestions and needle suggestion. Thanks
    pas, Apr 18, 2013
    #1
  3. HarleysLR

    HarleysLR Active Member

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    Where you live elevation wise makes a bit of difference on how you jet.
    80" Evo should be some where around a 45 slow and 175 - 180 main.
    I am sure you don't want to hear this but drag pipes do not function as well as pipes with baffles. However they are loud and lots of guys like that. A good set of pipes and baffled mufflers would help performance. JMO
    HarleysLR, Apr 18, 2013
    #2
  4. pas

    pas New Member

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    Elevation 50-100ft. East coast near water. Connecticut
    pas, Apr 18, 2013
    #3
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    How do you know it's running lean, was an AFR test done or do you have symptons of a lean engine, popping , yellow pipes, hot (well other than normal HD hot)...

    The best way to check the pilot jet size is to turn in the Air mix screw lightly bottom it don't crank on it or you'll fubar the carb, turn back out 2.5 turns.

    Then start it and get it warmed up, lock throttle at 1500 RPM
    Turn in the idle screw in until the idle changes, count the turns
    then turn the screw out, idle will return and keep turning until
    the idle changes again, counting turns.

    The difference between the two is the mid point.

    If you can turn it all the way in and the bike still idles or if the sweet spot is say one turn
    out the pilot is too rich, if you need to turn the screw out 3 to 3.5 turns
    then you are too lean, then you can play with jets,

    Typically the main jet needs no modification as EPA doesn't apply at WOT but you don't want to futz with mutilple things at one time.

    Once you get the pilot right then you can play with the needle shimming it up (richer or on the needle quicker) or down to lean it out...

    Pilot jet works up to about 1/3 throttle so while you cruise at 50 mph you may or may not be on the needle yet, so fix the bottom, set the mid and you should be good.
    hotroadking, Apr 18, 2013
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  6. pas

    pas New Member

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    I pulled plugs and they are white. I also want a little more performance out of my set up. My mixture screw isn't drilled out. I figure since I have to pull carb to drill it out might as well rejet and change needle. I've read most guys go at least 45 on the pilot.
    pas, Apr 18, 2013
    #5
  7. kenfuzed

    kenfuzed Administrator Staff Member

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    Hi Pas, moved this thread over to the general tech talk forum since its not specifically about product support for CV Performance products.

    Gaining access to and tuning the mixture screw is really important on these carburetors. Simply rejetting will only get you half way toward your goal and neglect the crucial tuning needed in the transition between idle and where the needle takes over.

    The following article talks about how to access and tune the mixture screw, with or without using an EZ-Just.
    Harley Davidson Carburetor Performance Tuning

    HTH
    kenfuzed, Apr 18, 2013
    #6
  8. Sir Rat

    Sir Rat Active Member

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    Pas, First of all welcome aboard. Second of all do yourself a favor and get one of the tuner kits from CVP. It will have everything you need as well as very detailed instructions. You can't beat the price and if you do have any questions, all the answer you need are right here. Good luck

    Aloha...Mike
    Sir Rat, Apr 19, 2013
    #7
  9. Lucifer

    Lucifer Well-Known Member

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    Yep...should start with a 45 pilot then follow HRK and Ken's instructions...

    My '90 80" Evo left the factory with a 45 pilot and 190 main
    Lucifer, Apr 19, 2013
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  10. hotroadking

    hotroadking Super Moderator Staff Member

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    BTW plugs don't really show color like they did years ago until you have oil issues or it's so rich it fouls the plugs.

    the ultra clean fuels today without led make it hard to tune based on plugs. Best done with the idle air screw and if possible on a dyno.
    hotroadking, Apr 19, 2013
    #9
  11. pas

    pas New Member

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    Last year at the end of the season my intake seals went. I replaced them and cleaned the carb. Nothing major. Since I put it back together. If I hit the throttle hard the bike feels like its starving for fuel. If I roll on the throttle easy not so noticeable. I adjusted the A/F today but no change. I wonder if my float level is off. I did kind of knock the carb around when I was cleaning it up. I checked the accelerator pump and it sprays strong when I hit the throttle. Any suggestions? Thanks
    pas, Apr 19, 2013
    #10
  12. Lucifer

    Lucifer Well-Known Member

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    Lucifer, Apr 19, 2013
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  13. pas

    pas New Member

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    Hopefully I can take it apart today. Anything else I should be checking while I have it apart. Bike ran fine before intake seals went. Possible slide problem? Any suggestions? Thanks.
    pas, Apr 20, 2013
    #12
  14. pas

    pas New Member

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    Got a chance to work on my bike the other day. After poking around found what the problem was. Carb was not problem. Ground wire behind coil had come loose. After fixing ground wire bike ran fine again but wanted to tune carb. Turned in A/F screw all the way no change in idle. Have to turn it out over 3.5 turns from seating to get idle to change. 1993 evo 80" motor with tear drop S&S air cleaner with K&N air filter and drag pipes. Right now has 165 main and 42 pilot N72 needle.
    pas, Apr 29, 2013
    #13
  15. HarleysLR

    HarleysLR Active Member

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    as suggested earlier try a 45 pilot jet and a 175,-180 main.
    HarleysLR, Apr 29, 2013
    #14
  16. Sir Rat

    Sir Rat Active Member

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    I'll bet he needs at least a 46 to start. IMHO

    Aloha...Mike
    Sir Rat, Apr 29, 2013
    #15
  17. Lucifer

    Lucifer Well-Known Member

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    Quite possible,but those drag pipes are a bitch....

    Good you found the problem....you're too lean,though... the N72R(richer) was stock on baggers and N72S was stock on FXR's and Softails in 1990-91...

    42 pilot is the 883 Sporty low jet...

    Here's a needle break down....hope it helps...

    http://bike-talk.com/forum/tech-tips/14983-cv-needle-information.html
    Lucifer, Apr 29, 2013
    #16
  18. pas

    pas New Member

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    From memory it's a N72S. I'm not 100% on engine. The bike is custom. I bought it in 2000 but from memory I remember the engine was 1993. I have the paperwork on the engine somewhere but who knows where right now. I have a Clymer manual that has Carb specs. It has my set up (42 165) for 1990-1991 Ca model. Which I know my engine is not. Same set up for 1994-95 models.
    pas, Apr 29, 2013
    #17
  19. pas

    pas New Member

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    The thing I wonder about is nothing happens when I turn screw all the way in and seat it.
    pas, Apr 29, 2013
    #18
  20. jammerj

    jammerj Member

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    If you adjust the float, do yourself a favor and cut a piece of scrap wood (a 2x4 will do) on a miter saw at a 20 degree angle, then just put that on your work surface, and place the carb spigot on the angle. It'll be alot easier,& accurate.
    jammerj, Apr 29, 2013
    #19
  21. pas

    pas New Member

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    I think the float is fine. I found the original problem was a loose coil ground. Now I'm trying to fine tune the carb with my set up. Thanks
    pas, Apr 29, 2013
    #20
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