K&N went on, problems have arisen
 

I put my K&N on last week, and since then it has the feeling of lost power. I get carburetor spits (backfires) at any low RPM low speed situation like say 25mph in 2nd gear will spit and sputter until I downshift. And it seems there is a noticeable flat spot before 4k RPM...

Is it too lean still...???? and YES it does have jets for the filter.

Make sure the block offs that came with the filter are seated properly. They're not interchangeable. If they aren't on right, your motor is drawing in air that's not passing through the K+N.

I will have to check that out... I assume they are seated correctly because I held them down as I screwed the filter box lid back on. I'm honestly about ready to put the old filter back on lol

did you go up in jet size?

Bought mine last winter, used over the summer, sold it in September. It would sputter and cough on part throttle at 2400 - 2700 rpm. Made parking lots and side streets a real pain in the ass.
I swapped the OEM back in and made a few comparisons. OEM was best by far. That and the recommendations of several other on the forum made up my mind

In my experience the use of a K&N filter requires radical rejetting. Sounds like it's still too lean.

That's what I would do (actually did). If I'd bought a bike with a K&N installed and it ran good, I'd leave it alone.

But from personal experience and all I've read, tuning to an aftermarket filter can be a pain in the ass and provides zero benefit other than the washability of the filter, which means it pays for itself in about 30,000 miles. Big deal.

Technically the benefit of such and airfilter is that it breaths more. However I do not know if that is the case with this filter.

Oh it breathes more all right. It just doesn't make any more power (even when jetted properly) and is a hassle because it necessitates rejetting.
I did like RK1 did. I took it out and put the stocker back in and haven't looked back. Maybe some day when I have a few hours to kill I'll try to jet for it.

So that probably means you need a Stage 1 to take advantage of that air filter.

Even that is debatable. There are lots of threads on the forum about experiences with K&Ns.
A K&N can be made to work as many here on the forum can attest, but there are no real gains to be had. It just takes time to get the jetting right.

just for clarity's sake, it's BMC, y'all...

Yeah, theoretically that's true. But just because a filter with a less restrictive element flows more air on a test bench doesn't automatically mean it will do the same thing in a particular air box.

I'm guessing here, but if the the aftermarket filter unit doesn't optimize the flow characteristics created by the air box it might not make more, or even as much power. And especially at low rpm- low load- low airflow situations it might run like shit.

Haaa, yes sorry I just orderd some parts for my mustang as I was posting that,,, On the bright side, I have a nice new BMR bracket coming for my panhard bar.. Which of course has nothing to do with the BMC air filter going in to my SuperHawk,,:D

a K&N or BMC is a good choice if your gonna put in the dyno time with someone who knows what they are doing, a DJ kit jetted no where near DJ's "suggested" jetting and if the pilots are stock they will need to be ever so slightly enlarged to get the low RPM/low TP cough to go away especially with aftermarket pipes...my mains are I think one size leaner then stock honda jetting, I foget where the needle ended up, pilots drilled with a #77 indexed bit(the smallest bit that would not fit through the stock pilots) also forget where the fuel screws are, the best with them is to set to DJ specs, then ride it, if you get decell popping then richen them slightly and try again it might not all go away so don't go crazy rich with them but you might get some of it out...mine runs perfect at all throttle positions now and will start with no choke unless its really cold out...but you have to get someone on the dyno with a lot of know how...between my boss and I we haven't had anything that was untunable and left not running well