New Bike Investigation (Carb)

Discussion in 'Dyna Models' started by 2003FXDX, Mar 30, 2011.

  1. 2003FXDX

    2003FXDX Member

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    Hi, I'm new here and new to HD's. I'm really impressed with this forum and find nearly any question I come up with has been answered in other posts or the self help sections. However, there is SO much information I get distracted and wind up reading page after page of posts and before I know it i'm off on a totally different subject than what I started looking for. I can't post a picture of my ride 'till I post a few times so here goes and TIA for your patience. I bought this 2003 FXDX with 16,500 miles on it for several reasons, I wanted a motorcycle again after doing without for over a decade ( I rode BMW's for 30 years), I know the original buyer well and know he took as good of care as local dealers could or would provide (I'm highly skeptical about the dealers quality of work though), I thought it was a good deal and figured I could get my money back out of it if I decided I didn't like it (I like it a lot!). Early on, the first owner had a stage one mod done by the dealer, SE II baloney cut mufflers, SE (K&N?) air filter/intake, and what appears to be a SE Carb re-jet kit (I have the box with several different new DJ main jets). I got most of the original parts from the first buyer, stock mufflers and air cleaner, main jet and needle. I have read several posts, here and elsewhere, about carb mods and was curious as to what exactly I have installed. I have had an issue with the engine spitting back through the carb when slowing to take a turn and even had it stall a couple of times after warm up when coasting into a gas station at idle. I gathered by the posts I read this indicates a lean idle mixture and so tried adjusting the idle air mixture screw. I found it was about 2 1/2 turns out and did much better @ three turns out. Today I took the carb off to see just what was in it and found a #45 pilot jet and a DJ main jet #180. The needle appears to be stepped rather than a smooth taper and is adjustable with six slots for the horseshoe clip. It also has three washers on top of the clip. The clip is in the third slot up from the bottom. The slide vacuum hole has been drilled, a 1/8 drill bit is a loose fit. My first question is; If I continue to have coughing through the carb, should switching to a #46 pilot jet be in order? Is a #46 jet preferred regardless with this configuration? Does this setup sound reasonable? I have done the wide open throttle test and in third gear between 3000 and 4000 rpm there is no noticeable stumbling or surge when I back off a little (1/8 turn), this indicates the main jet setting is +/- good, no? Any thoughts, comments questions, answers or suggestions?
     
  2. glider

    glider Veteran Member

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    WOW! You said a mouthful but that what's we like to hear, all the facts :s

    Here's what I recommend, first off the DJ kit isn't the best choice I have found over the years that it isn't the best choice as far as maxing out the potential of the motor or MPG and you have the DJ needle in there with the clip, multiple settings for the clip and washers.
    Unfortunately the slide being drilled IMO isn't the best way to go either because it can cause a stumble under certain conditions. If you have the stock needle, I would suggest reinstalling it with 2 washers under the head of the needle for best performance. A #46 jet would probably stop the popping and possibly a 185 main would help out too in that bike. Idle mixture should end up at about 2 1/2 turns open with the right jet in there. This you adjust to the highest and steadiest setting warmed up and then just a hair closed to lean out the fuel will give you a nice crisp throttle.

    Most times it's much better to just get the proper jetting and install it than the DJ kit which isn't cheap and in many cases doesn't turn out the best results.

    Other than that it sounds like you have all the necessities for the mix with the intake and slip ons.

    Good luck and enjoy the bike.:D
     
  3. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The letters DJ would tend to indicate that it is a dyna jet kit that is fitted
    I would personally prefer to use the stock needle and jets however if it runs ok in the higher rev ranges then perhaps all that is needed is the next size up in slow jet just to get it a little smoother at low revs

    Brian
     
  4. 2003FXDX

    2003FXDX Member

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    Thanks for the tips. The weather cleared enough for another test ride to make sure I didn't screw it up too bad, so I started out with the slow mix screw out about three turns and after riding 5 miles through stop and go traffic I got another pop through the carb. I stopped at my brothers house and borrowed a screwdriver and turned the screw in till the motor slowed a bit then out a turn and a half before it sped up and smoothed out some. I reckon it's out about 4 turns now. During the next leg of my ride I still had one pop through the carb when I slowed to turn around on a dead end. It seems to idle okay at stops but the pop is annoying and makes it clear to anyone within ear range it isn't running just right. Otherwise I can't complain about performance, keeping in mind this is the one and only Harley I've ever ridden so I have no comparison basis really, I have the stock main jet and needle so I think I'll try it. I'll also try to get a #46 slow jet. Another Q or two; when a dealer does this kind of mod on a carbed bike would there normally have been any change to the timing/electronics? And, I have washers on top of the kit needle I believe are the right size to use under the stock needle, does two #4 washers = .050"? Thought I read that elsewhere.

    Update: I now have the stock needle, tube and jet (190) installed with two aluminum washers that were part of the other kit under the needle. It seemed to me to run a little smoother on the top end, I'll have to wait for better traffic conditions for further testing tomorrow. I can't imagine wanting any more power on two wheels! It was starting to feel mighty light on the front end at 95 mph, I can see why the manual says "Do not exceed 80 MPH":D Had that pop again, just once, I read in the help files that having the vacuum hole drilled out can cause it. I'm pondering filling the hole with JB-Weld and re-drilling it a bit smaller. Now to find that #46 jet! Cheers! :cheers
     
    Last edited by a moderator: Mar 30, 2011
  5. glider

    glider Veteran Member

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    Proof that you need a bigger (#46) jet.

    If you can't get it locally, you can get it here...
    Pilot Jet #46 for Keihin Carb PN 400-861

    That's about what it comes out to be.

    That's true, under low RPM and cold temps, sudden opening of the throttle will bog out or pop from a temp lean condition.
     
    Last edited: Mar 30, 2011
  6. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

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    You could always buy a new slide. I did. It seemed to help over the drilled slide. I think J&P has them for a little less than HD. I'm thinking if that doesn't help maybe you should check for an intake manifold leak. I'm not sure that the circlips that come with the DJ kit are as fat as a standard #4 washer? May check that out to, as that wouldn't lift the needle as far. This months AIM issue has an article that suggest a sporty needle #27094-88 its taper is supposed to be better but I cant confirm or deny that but am thinking of trying one just for fun. The authr goes on to say that his opinion is that the .45 is the right jet for stock motors even with a stage 1. I'm not sure I agree but he swears by it. let us know how it works out for you.

    Bodeen
     
  7. 2003FXDX

    2003FXDX Member

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    The washers I salvaged from the kit are pretty thin, I'll see about getting some brass #4's from the hardware store, the two aluminum ones I used look to be about .025" total just by eyeball. I'll check for manifold leaks.
     
  8. glider

    glider Veteran Member

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    The 45 will be on the border of lean and the 46 will be a better choice. As far as the sporty needle, the taper on that needle comes from a carb that doesn't have an accelerator pump so it's rich when you put it in a carb that does have an accelerator pump. Your MPG will drop significantly as well as being overly rich in some areas of the fuel delivery.
     
  9. 2003FXDX

    2003FXDX Member

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    I have ordered the #46 pilot jet. In the meantime I want to inspect the idle mixture screw and parts to make sure they are in good shape. Problem is, the threads are apparently damaged causing the screw to bind up tight preventing me from removing it. Now I know I saw in a post somewhere on this site, the screw's dia. and pitch but cannot find it again to save my soul. I have the taps and I'm willing to modify one to attempt thread repair/cleaning If I can get the right size. Any chance someone can point me to that info? I'll keep looking but I'm running out of search ideas. :(

    ================================================

    Only 5 minutes to edit eh? Okay, anyway, I gave it a little squirt of PB Blaster and it came on out pretty easily. I don't think thread restoration is needed now but I'll try to match it up to a tap, who knows, I might even find my pitch gauge...
     
    Last edited by a moderator: Mar 31, 2011
  10. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    If you are going to replace the idle mixture screw then once you have the new one you will be able to measure the threads on it to get the correct tap but i am pretty sure it will be a metric thread

    Brian