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Hey guys, I was wondering if anyone has ever tried using individual filters on our stacks instead of running a after market filter topless?? I have tried doing this and the bike is running super rich and the bike is idling high.. The tuner had to pull crazy fuel out of the bike in order to run decently, and it still has a stuble at low rpm and decil popping. Do you guys think it could be these filters causing this? Do you think because the IAC is getting less or more air its causing the crazy idle?? Any info would help.. thanks again! And its a 1250 with bub 2-1...
 

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Hey guys, I was wondering if anyone has ever tried using individual filters on our stacks instead of running a after market filter topless?? I have tried doing this and the bike is running super rich and the bike is idling high.. The tuner had to pull crazy fuel out of the bike in order to run decently, and it still has a stuble at low rpm and decil popping. Do you guys think it could be these filters causing this? Do you think because the IAC is getting less or more air its causing the crazy idle?? Any info would help.. thanks again! And its a 1250 with bub 2-1...
How did you install these individual filters?
Did you remove the velocity stacks and replace them with a tube that the filter is attached to?

I'm not a big fan of this "individual filter" technique for a couple of reasons.
  1. It's very difficult to get individual filters with filter areas equivalent to the stock filter. Since only one cylinder at a time pulls through the stock filter, each cylinder sees a rather large filter area. However, when using individual filters each cylinder is forced to use a smaller, more restrictive filter.
  2. You also have a problem with the idle air bypass port not being filtered.
I'm not sure why you're seeing an high idle, others have done this "two filter" technique to provide extra room in the filter box for "accessories" and haven't reported idle problems.

Do you have a DTC set? When the ECM idle set point can't be achieved a DTC is set for lack of idle control (P0505) and this will activate your "check engine light".
 

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K.I.A. '07 AW
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Discussion Starter #4
How did you install these individual filters?
Did you remove the velocity stacks and replace them with a tube that the filter is attached to?

I'm not a big fan of this "individual filter" technique for a couple of reasons.
  1. It's very difficult to get individual filters with filter areas equivalent to the stock filter. Since only one cylinder at a time pulls through the stock filter, each cylinder sees a rather large filter area. However, when using individual filters each cylinder is forced to use a smaller, more restrictive filter.
  2. You also have a problem with the idle air bypass port not being filtered.
I'm not sure why you're seeing an high idle, others have done this "two filter" technique to provide extra room in the filter box for "accessories" and haven't reported idle problems.

Do you have a DTC set? When the ECM idle set point can't be achieved a DTC is set for lack of idle control (P0505) and this will activate your "check engine light".

What we did was trim the radiused portions of each stack off and slide the small k&n over each stack... the bike made 109 hp on the dyno, I dont have the chart with me so I do not know the tq #'s
 

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What we did was trim the radiused portions of each stack off and slide the small k&n over each stack... the bike made 109 hp on the dyno, I dont have the chart with me so I do not know the tq #'s
A HP or torque number reported by a Dyno test is only "relative". A Dyno number is meaningless without the number measured before an engine mod (same Dyno, operator, and preferably atmospheric conditions).

What you did was shorten the velocity stack length, degraded the in-flow (increased turbulence), and lowered intake port air pressure with a more restricted filter. It also sounds like the air for the IAC is unfiltered. None of these are good things but they don't explain your high idle.

It would help to know if your CEL is on, indicating a P0505 DTC.
 
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