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Can a K&N affect fuel mixture?

Sorry if this sounds stupid,

I've got a CIS 930 euro(1981). I just switched to a K&N air filter. Its' supposed to flow quite a bit more air then the stock paper filter.

I'm wondering is it possible that the added airflow could cause me to have to adjust my A/F mixture?

The reason I ask, is because I'd figure if it did change the mixture,... it would make it leaner,...and that ain't good.

Or does the added air flow have no affect on the actual mixture?

Thanks in Advance
Old 04-13-2007, 08:00 PM
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Crotchety Old Bastard
 
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That's not a stupid question at all.
I have never heard anyone say anything to that effect and have never seen any data to support it either way. I can tell you that I have adjusted my mixture with the air filter removed and then checked it when the fiter was replaced and saw no difference in the CO reading.

Personally I think K&N filters are a joke. They clean up your engine bay but I would be hard pressed to believe they significantly increase power output in any engine without also decreasing the filtering capacity. Stock filters aren't that bad.
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Old 04-13-2007, 08:45 PM
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A K&N certainly leans out certain carbs BTDT, not sure about CIS or AFM's
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Old 04-14-2007, 05:38 AM
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Hi Gents,
If you believe that the K&N makes more power, it would have to move more air and thus need more fuel ad mixture. Therefore it should lean you ourt some. I've never seen one do anything much either except ake more intake noise, and clean up an engine.

Les
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Old 04-14-2007, 06:29 PM
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i take it your talking about a replacement filter.its good since you can wash and reuse.and since it uses oil i guess it would filter better.if it does flow more air than you wouldnt have to change the air mixture.cause if it gets more air then the plunger on the fuel injection would go down abit more and give you more fuel.just like nathen says carbs would be different.
Old 04-14-2007, 06:41 PM
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On CIS no, the airflow sensor plate will meter any extra airflow and allow more fuel to compensate.
On a CIS 930... everyone says there is little or no power increase.

With a mass airflow meter and EFI after some time yes, because some oil from the filter will eventually leave a fine coating on the sensing element which throws off the signal to the ECU a little bit which will change the fuel mixture.

With carbs yes, The midrange and topend will be leaned out a little bit. Rejetting the carbs will make the mixture correct and you will have a little more power.
On a motorcycle the tapered metering rod will need to be raised a little along with a larger main jet installed.
Results will be no flat spots and a little more power.
Old 04-14-2007, 08:50 PM
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Not to mention the cone sounds nasty on spool up. I didnt spend any more money than I had to- I used an Edelbrock trianguler filter like you would find on a carbed 350 v8---------$40 AutoZone
Only mod I had to make for it to fit was clip out a little section for the Co adjusment screw.
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Old 04-14-2007, 09:49 PM
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i used one of those(edelbrock)till i noticed dirt was on the plunger plate.it doesnt filter to good.if you do decide to keep it put greese along the edge of the foam were it meets the base.
Old 04-15-2007, 02:56 PM
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That is a good idea, what I did was take a filter element from one of the HKS intakes (smaller bubbles?) and stuffed it in ther instead. Because the new foam was larger, I guess it wedged itself against the base harder than before thus eliminating my problem. I did notice the same thing as you.
Another thing that you could do is take some K&N filter oil and apply it liberally because there is no hot wire like in the new mass airs that go bad
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Old 04-15-2007, 03:20 PM
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