Stage 1 kit

Hi Ken,
Stage one kit made a huge improvement on my 883 sportster, However i am still experiencing the ocassional cough through the carb . It is not near as bad as it was. My settings are 3 turns open on idle mixture screw with the 44 pilot jet and needle installed with the se slide spring and 175 main. Have vance and hines slipons with quite baffle and kuryakyn hifive aircleaner assembly. Plug color on insulator is a light brown so it appears the mixture is pretty good. any suggestions to eliminate this coughing completely ? 2006 883
Thanks tim hahn

Thanks Chucktx i will give it a try, i already have a marked screw driver from when i intially was tuning this.
Tim

Hi Ken,
I tuned this with the engine definitely warm, the stumble or cough happens but it is not very often it is considerably better then the factory settings and the engine has got some pretty good midrange punch. One instance was i was cruising for about 1 hr at between 45 to 55mph had to stop and pay a toll, went to accelerate away and it spit thru the carb three times in a row and then it did not do it again for the rest of the ride. Also the three turns open on the mixture screw just started to color the insulator on both plugs a very lite red/tan , (i believe i said lite brown in the previous post) any thing less then that and i had a white to eggshell colored white. I wonder if stepping up to a 180 main might help as the needle works in conjunction with that jet . I am also getting some pretty good fuel milage with this setup just recently checked it two different times , one time 47mph and the other 51mph and that is a mix of city and 70mph+ highway riding.
Thanks
Tim

Hi Ken ,
Anything obvious to look for with the accelerator pump?
Thanks Tim

Thanks for the info Ken, i will check it . i also would be interested in trying the other needle that you mentioned earlier.
Thanks Tim

Hi Ken ,
seems just opening up the mixture screw a short 1/8 of a turn has cleared up the cough.Fuel mixture screw is open to 3 and 1/8 turns but i think the difference is the air cleaner, previous was an Arlen Ness big sucker and now it is The Hifive Air cleaner which seems to be alot less restrictive
Tim

05 Fatboy

I have the same problem with the coughing. It has done this since being new off the showroon floor. I've added the dynojet kit and this somewhat alleviated the problem, although it did not eliminate it.

hi Ken,
It appears i jumped the gun with the 1/8 turn more stopping the coughing with the high five air cleaner, because it did not, what was good with the big sucker is way off with this air cleaner. I am opened to 4 1/2 turns and the coughing is basically gone but i am also concerned because the spark plug insulator is still white and i would like to see it turning to light tan/red. Since the fuel mixture screw is this far open , i am going to up the pilot jet to a 45 and also purchase a 46 just in case. My questions are how may turns should i start with or close the mixture screw to with the 45 and do you think the nokk needle is still okay or should i shim it up?
Thanks Tim Hahn

Reading a plug is different now as the tan we all used to try to get was caused by the lead in the fuel. What we used to read as slightly lean is now really almost fat. I look for a Navajo white. As long as I can see color on the flame front side I know I am in the ball park. If it is scary white then I determine where it is lean and ge from there. I use Champion RN12YC for EVO and RA8HC for Twinkies and XL's.

From the factory, the engines are set extremely lean in order to pass idle emissions. On a stock or near stock bike, the pilot jet is usually very close or maybe one size to small. There has been a real tendency to throw a large pilot at an off idle pop when the problem may not be idle jetting.

For example, drag pipes, free flow air cleaner and a quick blip on the throttle will almost always get you a pop and it is hard to "tune" around it.

Your engine can only use so much air. A High Five, Big Sucker, Stage one, velocity cone etc will all provide all the air the engine can use. However... using the wrong type or a poorly designed air cleaner can result in tuning issues. A velocity stack on the street can be more difficult to tune than a Big Sucker or a Hi Five. An intake with a poorly designed inlet with no radius or tuning ring (the little plastic piece we used to install with SE air cleaners) cause turbulence as the air turns the corner...cause a PITA to tune.

There are only two ways to to tune.. well three I guess. Plug chop, dyno and wrong.

The Dyno is the most accurate by far and a seasoned tuner can do nearly as well using the old plug chop method but not one tuner that I know will try to tune using a "plug average" Trying to read a plug that's been run several times over several changes will net you confusion....

I wrote a few articles over the years and this one gives you a primer on tuning using the plug chop method.
http://bike-talk.com/forum/faqs/new_faq_item/

BTW, at 4 1/2 turns out, the tip of the needle is literally at or past the metering port entrance so you are not really getting any pilot jet metering from the screw.

At how many turns open does the engine fall off? If you turn it in until it stumbles and slowly back it out until it settles and then add 1/8 - 1/4 turn, you should be good to go. If you still have a pop, then you may have something else going on. An intake leak, low fuel level, weak spark etc....Even the type of exhaust can make life difficult.

Hi cd,chucktx,
Thanks for all the info so far. I have installed the Stage one kit from Harley Performance. When i had the big sucker on i had the fuel mixture screw turned out to 3 turns and had no coughing going on at that point and the plug insulater had a very light red/brown color to it and no black smoke out the tail pipe. I changed to the high five Air cleaner because i got sick of the breather oil build up in the AC and dripping out on my pants leg. And at that point the coughing returned. i did a plug chop and found that the insulator was pretty white at 3 turns . so i have progressively opened the mixture screw and have slowly almost eliminated the cough but not quite completely. I remember Ken"s comments about the 4turns out you probably need to jump up a jet size. The high five is definitely less restrictive then the big sucker, the sucker filter was completely covered the high five is not.my current set up is the stage 1 from Ken with a 44 pilot and the nokk needle with stock main jet i am only thinking of jumping to a 45 pilot to start.Just a note at this point right now there is no black smoke out the tail pipe unless the enrichener is pulled out about half way.
Thanks Tim

Tim,

When you say plug chop how are you doing a plug chop for the idle circuit? Remember, once the vacuum signal across the idle port drops off, the idle circuit is not in play. In essence, you cannot do a plug chop to determine idle mixture. You can set the idle, add new plugs and ride around a bit and get an idea if the idle circuit is close but if you use just a bit too much throttle you are reading off of the needle and the idle circuit. I use the same signs that you've mentioned. Exhaust color i.e. black or soot or nice and clean etc, throttle response and careful attention to needle position. When I invented the EZ-Just needle, we used a cut away of a CV in order to understand exactly what happens in the idle circuit. We measured the taper and length of the tip and how far it would protrude (or not) into the venturi fully closed and how far out does the needle have to be before the tip and shaft had no effect on tuning. We also tested to see if all fuel flow was cut off once the tip was fully seated.

After a lot of trial and error and wasted brass we determined that a slightly different taper produced a more linear adjustment in idle mixture. DynoJet produced our needles for a while and tested them for us. They came to the same conclusions we did.

This is a long way of saying that the needle has little or no tuning effect after about 3 1/2 turns out and zilch at 4 turns out. Additionally, at 4 turns you run the risk of loosing the needle from lack of spring tension. At 1 1/2 turns to about 3 turns the needle has the most effect. This is because the tip is very close to the venturi at that point. Below 1 1/2 turns the mixture needle begins to severely impact flow. If you look at the image you can see how both the tip and the smooth part of the needle can effect tuning.

It is very easy to go too large on the pilot to try and cure an off idle pop. A 45 might work just fine but it is by far the largest pilot I would ever consider using on an 883 even a sea level.

If you still have the pop temporarily install the Ness and test again. You can also remove the element and test. By eliminating any restrictions to air flow you are leaning the mixture more. If the Ness is more restrictive at idle, you would be making the idle circuit richer. The pop should get worse if the element is removed because you are flowing more air even though demand remains constant. The opposite will hold true if the Ness is indeed more restrictive at idle.

What else could be the cause of the pop? Have you checked for intake leaks? When you adjust the idle speed and mixture are you making sure that the butterfly (blade) is as closed as possible? It is really easy to chase idle tuning in the wrong way. To get the most throttle response off idle, you must have the minimum blade angle to get the proper idle RPM. This gives you the highest vacuum signal when you open the throttle. So, tuning the idle involves the blade angle (how far the idle adjuster is moved), the idle screw and the pilot jet.

Generally, the pilot jet is correct when you can make the engine stumble at 1 1/2 turns or less. If the idle will not fall off at all, the jet is too large. If at 3 1/2 turns out the exhaust begins to puff black, you're too big. A 45 should be plenty big a 46 ould be pushing it IMHO. If after all of the above you still have the pop, I would dig deeper.

Hi CD,
First if i remember correctly the engine started to fall off at about 2 1/2 turns out at that point,opening up it starts to idle pretty nice this is with the big sucker installed. Second i set the idle screw and i am not sure if this procedure is completely correct by closing the fuel mixture screw till it gentley seated then set the idle screw till the engine was barely running,then i opened the fuel mixture screw back up this was all with the big sucker A/C . At worst the idle may be just a bit fast , no tach handy at this point need to pick one up. I have stock head pipes on this and V and H straight shot slip-ons with the quiet baffles installed (although not to quiet). The intake has not been disturbed on this bike since new and this thing was awfully lean from new popped like crazy and i complained to the dealer. Guess it is possible there is an intake leak from new. Will have to check.Bottom line is the big sucker A/C with this set up had the fuel mixture opened to 3 turns and no off idle pops. The only thing changed was the a/c and the pops came back. I am going to give the 45 a try and see what happens , i will keep you posted.
Thanks for all your and help it is much appreciated
Tim

Looks like the 45 pilot with the fuel mixture screw set at about 3 1/8 turns out has solved the problem. Took a ride with new plugs and tried to keep the throttle setting to about 1/4 to 1/2. took a look at the plugs after that ride and the rear plug was kinda an eggshell white with a hint of gray color to it and the front plug was an eggshell white. no poping thru the carb either
Tim