Still not happy with my jetting

Discussion in 'Engine, Fuel and Exhaust' started by SpringerSteve98, Jun 16, 2009.

  1. SpringerSteve98

    SpringerSteve98 Active Member

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    Well we tore into the carb once because it was running to rich, i was getting horrible gas mileage and a dead spot i felt i had to throttle past at 1/8th to 1/4 throttle. Also, it was coughing a lot while cold at low RPM. This is what we found in it.

    Pilot - 40
    Main - 180 (with the clip set way rich)

    We changed the pilot to a 42, and moved the clip up the needle (dropping it) two notches to lean it up. And after running a couple hundred miles it seems to have helped somewhat, but i don't think its right just yet. Here is what i'm looking at. The plugs seem awfully lean, the dead spot seems to have moved up the RPM range... and it seems to want to surge when i roll on/off at about 1/4 throttle. (65-75mph mainly) Also, no popping or coughing while i start now, but i've noticed after a decel, and roll back on it studders once, then goes. (i'm guessing, but would say at 2500ish RPM and low throttle) Like my cough is back, only in a different place. I want to tear into the carb again, and i'm thinking i just overcorrected, and need to richen it up one notch. And mabye go with a bigger yet pilot. The plugs seem to read lean, they are awfully white.
    Any help would be appreciated, or suggestions before i get in there again.
     
  2. glider

    glider Veteran Member

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    Last edited: Jun 16, 2009
  3. SpringerSteve98

    SpringerSteve98 Active Member

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    That post reccomends a 45-46 pilot and a 185 main... When i started out my 180 was set too rich. So i think i'm gonna try to keep the 180, only move it back tward lean one notch, (moving the clip down to raise it) and mabye put a 45 in... At this point i'm rather lost to be honest... Its surging and studdering in places... Lean or rich? Am i on the right track? Oh, almost forgot to add... When i run it wide open up to third at about 60mph then roll off there is no noticeable surge or studder.
     
    Last edited: Jun 16, 2009
  4. glider

    glider Veteran Member

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    I have run a 45 low jet in my evo but the trick is to balance out the circuits in the carb for a smooth transition between them and not change more than one thing at a time or you end up fighting yourself. Start with the low jet #45 and adjust the idle mixture, from there set the needle in the middle slot and put 2 #4 washers under the lip on the needle to raise it,, put in the #180 and try it then.

    This is based on free flowing intake and exhaust. If you have any different, it has to be different jetting then. (downsized)

    Look at the lower part of this post to test your jetting.

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community
     
    Last edited: Jun 16, 2009
  5. SpringerSteve98

    SpringerSteve98 Active Member

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    One last question. It said in the TC jet post about being able to rotate the carb to access the carb... Can i do this without taking off the enricher control and throttle cables? Just turn it a bit and open up the bowl to get to everything? Oh, and one last thing... Glider, YOU ROCK! fast response and knowlegable, Gotta love this forum.
     
  6. glider

    glider Veteran Member

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    You should be able to rotate the carb enough to access what you need to do without any problems, done it many times.

    The bowl can be accessed with a short screwdriver if it has the phillips screws in it without doing anything.

    Thanks!:s
     
    Last edited: Jun 16, 2009
  7. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Fill us in on the specifics again. Is your bike fairly stock with a Keihin CV-40 carb? Is the stuff in the carb stock or is it a DynoJet Thunder Slide Kit or some other third party kit?

    I have a '91 Dyna with the CV-40 carb. Frankly, I can't understand how your bike ran even remotely well with the jets you indicated above.

    TQ
     
  8. glider

    glider Veteran Member

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    TQ

    Adjustable needle, probably a DJ kit. May be worthwhile going back to stock parts, it would run better.

    Also the DJ jets are measured differently than the stock jets. That's why I say this.
     
  9. SpringerSteve98

    SpringerSteve98 Active Member

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    It is a dyno jet kit that i found in it, only two holes in the emulsion tube (a tell tale sign). The slide has already been drilled. The dyno jet kit called for a stock pilot jet. Which in my case was indeed a 40.. Most evo's run a 42.5 or 45 stock. This seemed like a fairly generic big twin kit from what i understand. I've just installed a 45 pilot and left the 180 as it was. I only broke into the bottom side. Gonna set the mixture and idle... then take it out and see what happens. I haven't ridden it since i just put the 45 in.
     
  10. glider

    glider Veteran Member

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    If you want some sound advice loose the DJ kit. I have removed many of them to be replaced with stock parts then go from there with the suggestions in the links. The usual rejetting should run about $7 with stock parts verses big $$$ for the DJ kit and most of the kit isn't used either.

    Get a new slide to and stop banging your head against the wall. They run about $40 but you will be much happier if you change it back to stock without the drilled port in the slide, take it from someone that has done it many times to get the bike running right for people.