Making an EFI 88" Twincam sound like a carbed engine??

Discussion in 'Dyna Models' started by Safehaven, Dec 20, 2009.

  1. Safehaven

    Safehaven Active Member

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    Didn't quite know if I should put this in the dyna section or the tech section of the forum, so sorry about that in advance!

    Okay, I have an 06 Streetbob and love how the bike rides feels and looks. I've installed some new pipes and changed the EFI maps to suit them but I cannot get over the fact that whenever I fire up my bike, the idle speed seems a bit high..

    It lowers a bit once the engine is warm but I love the sound of a carbureted engine that is just above stalling. I'm sure you all know what I mean by that.. Just makes me go :bigsmiley24:

    Now I was wondering if something can be done to get a similar effect on a bike with EFI?

    Thanks for the advice,
    Kris
     
  2. Hoople

    Hoople Account Removed

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    I am sure some of the "Nice Sound" you hear on carb bikes is also due to the profile of the cam shaft. EFI cam profiles have got to be so much milder to meet emission standards.
    The idle control/speed on EFI can be changed by using a SERT. The idle speed needed for the conditions at hand is chosen from a look up table inside the ECM.
    And like Smitty says, other problems can happen.
     
  3. Jack Klarich

    Jack Klarich Expert Member

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    We got away or so we thought with low idle and a cool sound in the old days but starving the engines for oil at low idle now days is a bad idea JMO
     
  4. Bud White

    Bud White Well-Known Member Retired Moderators

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    plus you have to have the higher idle to power the electronics to low and the batter will start discharging
     
  5. Safehaven

    Safehaven Active Member

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    hey Hoople,

    Sorry to bother you with this, but what do you mean by SERT? I'm sure you are not wanting to say Special Emergency Rescue Team, but nothing else comes to mind when I hear that expression! :bigsmiley24:

    Thanks to all of you for the comments so far. This really is an amazing forum to learn about something I love learning about!

    Didn't even think about the electronics. Not that it would be idling for ages, but that definately is a valid point. Although I assume as long as the alternator is turning, there will be a current available to charge the battery or at least feed the running lights on the bike.

    I'd have to measure the power output at any new idle speed then.
     
    Last edited by a moderator: Dec 20, 2009
  6. Bud White

    Bud White Well-Known Member Retired Moderators

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    screamin eagle race tuner sert
     
  7. Safehaven

    Safehaven Active Member

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    Hey Smitty,

    I tought that might be an issue..
    Just wanted to know if there was anyone who electronicall re-mapped the ECU and did not have any issues with that afterwards. I realize this would be difficult to tell since any issues would not immediately become apparent.

    you were spot on with your sound description though!

    Maybe I should get another bike when I'm rich enough to afford one, or buy a tractor and mount some different pipes on that! hehe.

    Anyway, I'll check with a dealer for different cam configurations in the future. But this will not be too soon as it is pretty invasive and expensive (I think).

    Thanks to all for the replies.

    This forum rocks!

    Dude, seriously, that was quick!

    Thanks!
     
    Last edited by a moderator: Dec 20, 2009
  8. Breeze3at

    Breeze3at Well-Known Member

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    Safehaven; I know what you mean. My twin cam sounds like nothing special idleing, my evo sounds good, my shovelhead sounds like a Harley is supposed to at idle. The shovelhead does have a lower idle speed, but still sounds lumpy around 950 rpm. Some of the loping is due to richness, and some is timing. Newer bikes run more advance at idle. In the early 90's you could buy a gizmo for the evos that turned off the VOES (vac.operated elec. switch.) at idle to make it sound like a older bike.
     
  9. Safehaven

    Safehaven Active Member

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    I'm sure the guy/girl will feel pretty flattered when I ask them if I can record the sound of their bike!

    Thanks for the replies, I'll be on the lookout for a good solution and post back if I come across anything interesting that also works from a reliability point of view.

    Take care,
     
  10. tobaman

    tobaman Member

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    the mechanic from hd dealer told me pretty much the same thing that i shouldnt set the idle rpm too low on tc. He said the tc would get a hard time pumping the oil up.
    i set the rpm on my dad's 00 rk just above stalling rpm...now it sounds like ba doom ba doom..not like the regular potato potato. But now, i have oil leak problem. just curious low rpm mightve caused this. Before i changed the oil, the rpm was already that low, and no leakage.

    so far on my carb tc 04 fxdx, idle 600rpm no leakage. the sound rhythm is quite different to the rk though. i just think that it's because the 1 in 1 pipe on se2 whereas the rk with thunder pipes.

    but my reg mech doesnt quite suggest to use the choke on cold carb. simply twist the throttle twice before pressing the start button, press start then rev up to 1200rpm then fasten the screw under.
    i notice the difference. with enrichner the fumes smell quite nasty, probably it burns a lot more fuel.

    if idling rpm is too low, what's the worst thing could happen?