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Regular or higher octane for Harley's

Discussion in 'Motorcycle Tech Talk' started by HellBoy, Jan 30, 2008.

  1. HellBoy

    HellBoy New Member

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    Good to hear from all of you. I think a better description of what I've been experiencing is hesitation, kind of like all things are going smoothly and then a little burp or stutter.

    I do wonder if that's from the low octane gas or the tuning and my straight pipes. I'll have to wait until I have some free time and the weather improves a bit before I can have it looked at. I'm going to use medium octane until I get to the bottom of the 2003 Sportster regular gas recommendation. The guy I bought it from was adamant about never using high octane and I could hardly believe it.
  2. chucktx

    chucktx Moderator Staff Member

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    i believe it is your tuning. what you are experiencing is a lean condition. if you are carb'd back out the slow screw just a bit........if efi, it is map time.....:)
  3. maxpower_hd

    maxpower_hd Active Member

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    I have to agree. When I had my Sporty, a 1997 that I bought used, it had Revtech pipes, a jetted stock carb and stock air cleaner. It had similar issues. The PO played with the gap on the plugs to try to compensate. I ended up replacing the module and coil with Screamin Eagle stuff, installed a Mikuni Carb and a high flow air cleaner with a breather kit, better wires and new plugs (correctly gapped). That opened it right up and it ran great after that. My brother still has it with the same combo about seven years later and it still runs great.

    It was a 1200XL by the way.

    Hope that helps.
  4. DKIN21

    DKIN21 New Member

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    ran the middle grade one time, thought the valves where coming thru the top, nothing but high octane for me

    DKIN21
  5. SPORSTERBOY

    SPORSTERBOY New Member

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    Got A Guy Here That Runs A Shop Out Of His Garage, Told Me Once That They Casted Over The Adjuster Screw On The Sporty Carbs, Said You Could Grind It, On The Right Spot And Do All The Adjustment On The Original. Never Let Him Do Mine To Varify If It Was True Or Not.
  6. HellBoy

    HellBoy New Member

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    If weather permits, I'm going to Brooklyn HD tomorrow and will try to get some of these questions answered.
  7. HellBoy

    HellBoy New Member

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    Harley dealer in Long Island City, NY said he'd never heard of such a thing. I'm going to get a Stage 1 upgrade to prevent hesitation and will ask the mechanics what's up.
  8. duke76

    duke76 New Member

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    That is correct but It is on all late model cv carbs, not just sportsters, epa does not want any body messing with the idle air mixture screw and they are set super lean to meet emissions standards, that is why they are so cold blooded, if your bike takes forever to warm up you would certainly benefit from adjusting that screw. Todd
  9. HellBoy

    HellBoy New Member

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    So THAT"S why it takes so damn long to warm up. I usually start with the choke out and tap it back in slowly over a 20 minute period. It's winter here in NYC and perhaps it won't be so bad when the temperature is higher. Since my bike came with drag pipes I'm going to try the Stage 1 kit. It might help with the hesitation I'm experiencing. Hopefully it wasn't due to using regular gas. I just tried high test and it seemed to run a little bit smoother. I'm not sure if I'm imagining it yet.
  10. duke76

    duke76 New Member

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    I found an article on rejetting a sportster cv carb and it explains with pictures how to drill out and adjust the idle air mixture screw, here is the link. Todd

    Sportster CV Carb Rejetting
  11. fujimo

    fujimo New Member

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    stage one

    like maxpower said ,,,do the mukini first,,, will surprise you,,,pops
  12. chucktx

    chucktx Moderator Staff Member

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    hellboy, your sportster may have come with cv carb on it....if it is still there it is a great carb. very easy to adjust and change jets in it. there is a kit available through the owner of this board to modifiy the cv carb. i have messed with carb and kits for over 40 years and i feel it is the best bang for the buck for the cv carbs, and anyone can do the mods. (disclaimer....i am in no way affiliated, or get any kickbacks from this kit) i just know it works, and works great!!!..............:)
  13. duke76

    duke76 New Member

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    I totally disagree with getting a mikuni, there is nothing wrong with a cv carb, and they can easily be tuned to run just as good as a mikuni, people are just more familiar with the mikuni and that is why so many people use them. You can do what you want it is your money but you could spend that money on cams or chrome instead of the carb. Todd
  14. HellBoy

    HellBoy New Member

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    Thanks guys. I do have the original carb. I'll ask the dealer's mechanic about the adjustment screw and if he plans to make it adjustable. I could also get that adjustable pin that HD Performance sells..
  15. whacker

    whacker Active Member

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    Wouldn't be a bad idea to check into what chucktx said about the CV .....
  16. voodoochild

    voodoochild New Member

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    Ditto, Ken has been messin with these carbs for alot of years....testing, developing, etc. It's definitely worth a shot. BTW, I have the same disclaimer as Chuck....:D
  17. hotroadking

    hotroadking Super Moderator Staff Member

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    Sounds like a typical lean carb standard issue on all HD's with a carb, (Or efi for that matter) it's all about lowering emissions.

    On the bottom of the carb behind the float bowl as you'll see in the diagrams offered above is a small cap over the screw, you can drill a small hole and pop out the cap.

    The main jet on your carb is probably fine, there are not EPA regulations on emissions at WOT because people rarely spend any time there, it's all about low speed and cruising speed.

    You should put on the HD SE air filter kit or Arlen Ness Big Sucker kit, if the HD kit no longer contains the K&N style cleanable filter, don't buy it, tell the dealer you want a Ness Big sucker and order it, better to wait for the K&N style cleanable filter so you don't have to keep buying air filters from the dealer at $40 a pop

    Pull the float bowl and see what jets are in the carb that way if you take it to the dealer and they "change things' you'll know if they changed the jets and you have a baseline for the changes to work from.

    Usually just seating the air mix screw (very very gently) then back out 2 turns, warm it up, hold idle at 1500 then turn in counting turns until idle falls out, turn back out, counting turns until idle backs off, then center it.
  18. HellBoy

    HellBoy New Member

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    Thanks HotRoadKing, much appreciated. I just dropped off the bike at the Harley dealer. The guy at the repair dept. was cool. It was my first time there with my Sporty 883XLH and he offered some helpful suggestions. I diid order the Harley Stage 1 kit, I'll check on which air filter ASAP. They're looking into finding the correct baffles for my straight pipes and will rejet the carb. The screw for adjusting the fuel mix didn't have anything in it's way, so I assume the previous owner had it changed. I figure it'll cost me $200 more than if I did it myself, but I wanted Harley to sign off once on the bike for future reselling purposes.

    The repair dept. guy said that the Sportster CV carb is a "cold blooded" animal and might still give a burp or two even after the work is done. He did feel the Stage 1 upgrade was worthwhile for performance reasons, but advised me against bothering with an 883 to 1200 cc upgrade. he thought it wasn't worth the cost and that since I'm 6'5" I might want to enjoy the Sportster while getting accustomed to riding and then eventually look at a Softtail.
  19. voodoo1

    voodoo1 New Member

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    miks and CV

    My buddy and I just put a Mikuni 42 on his softtail. I like adjusting them so for me they are fun.
    They let more airflow in much quicker than a CV(look at the stats.... So the seat of your pants "romp" is noticable. He loves it. I run a CV off a sporty from 97 or so that I have put on everything since I got it and work it. Needle jet,etc. Oh yeah I sold it to him...... His bike took to that mikuni big time and the work done to the bike made it a real fit. My Humble Opinion is HRK has it right on. If those stage one changes make you happy. save your money and ride. Ever heard of the slippery slope? :cool:
  20. chucktx

    chucktx Moderator Staff Member

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