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Thread: P0026.1aa and P0027.1aa fuel injector

  1. #1
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    P0026.1aa and P0027.1aa fuel injector

    do they make aftermarket injectors or upgraded one? For 2006 buell ulysses xb12x

  2. #2
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    With an aftermarket muffler, K&N, and opened airbox I was maxing out my injectors. I upgraded the fuel pressure regulator to a Delphi FP10153 which increases the fuel pressure from 48psi to 58 psi. After the big bore kit I was again maxing out my stock injectors from 4000 rpm on up and my AFR was going lean up into 14's while WOT! So I installed Siemens FI11420 (108-420) injectors which are 42 lbs/hr at 43.5 psi. They drop right in and are plug and play. I had to lower my fuel maps across the board about 30% so the common quote of 30 lbs/hr for the stock injectors sounds about right. The stock injectors have custom pintles that angle the fuel spray. The aftermarket ones do not and I could not find any that do. I did not see an easy way to swap pintles without damaging them. For big turbo setups you can run Siemens FI114962 (107-962) which are 60 lbs/hr. With the 108-420 injectors I still get good idle quality and headroom at high rpm. I have also read that some lower the closed loop areas of the map to skew the AFR higher to get more fueling at the top end. I did not try that and found it easier to just swap injectors.

  3. #3
    Senior Member Cooter's Avatar
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    Injectors with the flow rate [you calculate] you need, but for a Sportster application, will have the correct spray pattern and angle. It's important enough to do right, even though you already bought other ones.

    Sort of surprised you need them with a big bore kit? OE Buell injectors can support quite a bit of HP! Maybe getting the stock ones cleaned and even modded is an inexpensive option for you thats better than them shooting the wrong direction?

  4. #4
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    I’m surprised also. Im not even close to maxing out the stock injectors. I have a 9 though

  5. #5
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    Cooter do you have a part number or reference to Sportster injectors? From my research I could not find injectors with angled spray pattern like the stock ones. The ones I installed are a 4 hole, 30 degree cone spray (vs. pencil pattern). I did send in my stock injectors and had them cleaned and tested when I did the big bore kit. It made no difference. From 4000k to redline I was running max opening on the stock injectors front and rear cylinders and my AFR was climbing into the 14s. AFV locked out at 100, running open loop, on my wideband. I have a 09 XB12R with headwork, cams, big bore kit, ported TB/manifold, open intake, and open exhaust. Hard to say if engine combo, weather, altitude, etc. are determining my fueling needs. I have not had it dyno yet with the new setup. Need to get my fuel maps/AFR dialed in first. It's a beast that's for sure. Fun bike.

  6. #6
    Senior Member Cooter's Avatar
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    I don't, so '09-up Sportsters are FI. I'd look there. It's my understanding they have the same front rear pattern as a Buell even though the intake is a 90*. But I believe Buell injectors already flow more than those OE. My idea was to find you broader application option to help you find yourself bigger ones that actually point in the right direction. The factory thought it was important enough to make special ones, and they are smarter than me so...

    IMO, I'd start with why you think yours are "maxed out". Double check every source of your info. I have messed with very modified Buells that put out a ton of power and use stock injectors. Mike L can concur with his stock injectors and a dyno sheet that impresses!
    Reading 14:1 at WOT isn't dangerous and technically still "rich", just not making max power like 12.5-ish:1 would.

    If you are certain your bike needs that much more fueling it might be an easier path to have yours flow tested, try a new set of OE, or have an OE Buell set modded to your liking. How big is your "big bore kit"? Massive? 1600cc?? Woo Hoo!



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