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Drop in fuel economy after installing K&N air filter

6428 Views 11 Replies 8 Participants Last post by  Colonel
I just installed a K&N re-usable air filter. Prior to the change, I was getting about 40-41 mpg. I'm now at about 35 mpg. There is a very minor almost negligible improvement in performance, but nothing to justify a 5-6 mpg drop in economy. Has anybody dealt with this before?

The only thought that comes to my head is that the new air filter allows more air in that I have to remap the fueling??

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How about it being over oiled? That was always the nightmare of using them, the oiling.
Well, here's the thing, I've always oiled them for the dirt bikes but the instructions did not specify the need to oil them nor was any oil included.

Other than now being extra air that may require an adjustment in the fuel mapping, I can't think of any other reason. A friend said to give it time, but it has been two rides totaling 400 miles so I'm at a loss.
I swear they have to be oiled, dont they? Do they now come pre-oiled?

It the filter media red?

If it is dry...I dont know..The air filter is not the restrictive thing on this engine,its the exhaust. I just dont see it causing the issue.
Air Filter

I swear they have to be oiled, dont they? Do they now come pre-oiled?

It the filter media red?

If it is dry...I dont know..The air filter is not the restrictive thing on this engine,its the exhaust. I just dont see it causing the issue.

It looks like the KA-1111 is the K & N replacement filter for Ninja 1000. Most come pre-oiled. The filters are made of cotton guaze. They are suppose to be re-oiled if washed and dryed. K&N has its own oil for use.
The KA-1111 is the specified filter and the one I installed. The brochure literature said that the KA-1111 "fuel management modifications not normally required".

I dug up K&N;s telephone number, 800-858-3333. I plan on calling them on Monday and see what, if anything, they can suggest.

My only other option is to purchase a stock air filter and run it for a while and see what happens to the fuel economy....
When I installed the K&N on my Honda ST1300 I also noted a slight drop in fuel economy. Disappointing,,,
I have never experienced an improvement from the K&N filters. Usually my motivation is to have a re-useable filter, but after washing/oiling the K&N a few times I realized this is a fool's errand. More so if your MPG drops enough to offset any cost savings.
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I too have never replaced an air filter with an aftermarket one expecting better fuel mileage. Most are touted as high performance & that's what I look for. I'm a fan of BMC filters as I think they fit/seal better. Speaking of sealing, did you check to make sure it's fitted properly?
I'm thinking you're spot on. If it flows better, the injection system is going to push more fuel to keep it at stoichiometric. I'm thinking remap may not help, either, since you've increased the total fuel need of the system by offering more air.
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I haven't had a chance to do anything regarding this issue. But I tend to agree with Mikey100. I'm going to have to undo everything and verify that the filter is properly seated on the housing.

Originally I didn't think that would be possible because in other bikes, a poorly fitted filter results in in less performance. In this case, the performance is very slightly improved but the mpgs for sure were way down.

I'll report back on this. If I leave it on for a bit I don't think it's going to hurt anything.
I installed a K&N air filter and it is a better fit than the BMC. The K&N's bolt lead hole is much better aligned than the BMC. However, it still isn't a better simple "drop in fit," like Kawasaki's OEM filter. I prefer the K&N's fit over the BMC.

In addition, the K&N came much more oiled. So, in my case, made in the USA is better than made in Italy, for this application. The truth is, both filters need a better fit. They are too tight, to drop in. The rim & eyelet needs work.

The good news is, the K&N is serviceable, no BMC headaches. Eyelet, the BMC is molded long and the K&N short. The K&N will align though. Do I recommend either? Hell no, but that's, what's available. Both are horrible. How hard is it, to find a regular fitting cleanable filter? Good thing it isn't a head or cooling gasket. If it was either, it wouldn't have aligned properly.

But then again, if you all think it's okay or if the companies think it, on ya'll but the BMC no. I'm going to install the same things. It isn't like I have a special factory at Area 51 for air filters. I'm not a magician. If it isn't an exact perfect fit, like, we all want, well, it just isn't.

- Aviation Electrician

:sad: Half breed insane infedils
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