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SNAFU
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Running topless means removing the top cover on the airbox clamshell. The results are more air flow into the engine. With the proper EFI map that equals more power.
 

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Color me Gone
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Running topless will also increase induction noise. How many remeber turning the air breather tops upside down on an old 4 barrel, sounds similar. It is good for a couple of extra ponies though.
 

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I have not had a noticeable decrease in mileage but a lot of that has to do with riding habits. Your ears will get treated to the rush of air flowing down the velocity stacks when you twist it hard though!:cool:
 

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I have been thinking about this, by running topless you increase the air intake, but doesn't that reduce the ratio for the gas mixture and cause a lean condition, at WOT?

With the top on you do reduce the availability of air, at WOT, but it's programmed to expect that and not for a more open intake.

I would be interested in seeing how this works over the long term.

Dave
 

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HD states that their new EFI downloads are designed to run with the top off, which would put you rich with the top on. That would work out great for the more conservative crowd.
 

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Geezer
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What I likes best about my 914 porsche with webers was the sound of those carbs right behind my head. I even removed the rear window so I could hear it better. I'll be trying the topless mode when I get the bike back Wed.
 

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spit happens
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Before I got the supertrapp exhaust,k&n fiter,and PCIIIr I ran topless with the stock mufflers.I noticed more throttle response.And it sounded meaner.All that air being sucked in there.Those throttle bodies are huge.Just remove your filter and look.
 

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What if ........

:What if you bought a spare cover (a 2003 model with mount for sensor) and cut a good portion of it away leaving only the sensor area(evened out of course) . Maybe the best of both worlds ? Just a thought.
BobT:confused:
 

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Color me Gone
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I have the original top for my 02 before I installed the updated IAT sensor, I may do some playing with it and see how it feels. I would do a dyno run but my idea was to open the front of it to work like a scoop and I don't think a dyno would show the effect with out the wind rush effect.

Max
 

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SNAFU
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It all comes down to whether you are running negative or positive pressure in the airbox. Removing the airbox cover will not produce positive pressure but will get you closer to equal pressure. If you can open up the airbox cover to a size equal to or greater than the total diameter of both velocity stacks and create positive pressure at speed then you have the best of both worlds. I've thought about opening up the front part of the cover with some holes or slats to accomplish this.

One of the basic tricks we use with the Porsche 930 is to drill 6 1" holes on the bottom of the airbox, on the atmoshere side of the filter. That alone is worth 10 HP under boost just by eliminating negative pressure in the airbox.
 

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Color me Gone
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Yes sslegend, that allows more air flow to the throttle bodies. It has been documented to add horse power and now Harley Davidson even has a flash to compensate for running with the top off.

Max
 

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Thank you Max. If I have the power commander on the bike now, where do I get the new down load? I have the K&N, V-modded 16Gauge pipes. Where does the IAT sensor go with the top off? Thank you for your advice!
 

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Color me Gone
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I'm not sure about a download for the pcrIII, the donwload I refer to is from HD for the factory pcm. Some have commented that the pcrIII flash for the v-mods and k+n was designed to run topless but I can't confirm this. The IAT sensor can be attached anyplace, HD sells a piece of velcor now to stick it to the bottom of the lower section.


Max
 

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mjw930 said:
It all comes down to whether you are running negative or positive pressure in the airbox. Removing the airbox cover will not produce positive pressure but will get you closer to equal pressure. If you can open up the airbox cover to a size equal to or greater than the total diameter of both velocity stacks and create positive pressure at speed then you have the best of both worlds. I've thought about opening up the front part of the cover with some holes or slats to accomplish this.

I have done exactly that. I'll snap some pics next time I have the skin off.


John
 

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If You Ain't Cav...
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sslegend said:
Thank you Max. If I have the power commander on the bike now, where do I get the new down load? I have the K&N, V-modded 16Gauge pipes. Where does the IAT sensor go with the top off? Thank you for your advice!
sslegend,
We are running almost the same setup. This is the map I run and the bike loves it....
M809-018 - Screamin Eagle 16 Gauge Double slip-ons (without baffles), Stage 1 ECM and Screamin Eagle air filter

I pop out the sensor part of the top cover, reattach and put inside the open airbox, secured with a piece of elecrtical tape! Works great for me.

Mike
 

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John, I would be interested in seeing that too.

If you open up the airbox cover in front, but leave the rest mostly intact (top, sides, back), does that result in less ear sucking sound?
 
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