Air cleaner choices?
There are also dozens of different looks.
Probably most important, it is one of the few air cleaners that is not feeding hot oily air into the intake from the breathers.
If you ever have a chance to put your had near the air coming out of the rocker cases and being fed into the intake (without filtering) you might be surprised how much there is and how Hot it is.
The oily component of that oxygen depleted air is not doing your combustion chamber any good either.
Let me clarify this: Imagine the air filter assembly to be a round cake, that is installed "sideways' on the bike. The bottom of the cake attaches to the throttle body. The perimeter of the cake draws air. I want the TOP of the cake to also draw air. The only air cleaner type that does anything like that is the HD Extreme Billet and a similar design from Ness. If you examine the page in the HD Screamin Ealge catalog that shows replacement filters for all the HD air cleaners, you will see that the only filter that draws from the "top of the cake" is the Extreme Billet.
Jim G
But . . .
the fitment statements for all the aftermarket air cleaners I have seen fail to address any configuration other than "stock" motorcycles (understandably). But, I don't have a stock motorcycle. I have a Breakout with a non-stock 58mm throttle body because I have the Stage 4 race kit, so looking at aftermarket air filters would do me no good: I couldn't know which ones would fit.
To make things worse, there are 2 different 58 mm throttle bodies:mechanical, and fly-by-wire. Only harley itself addresses all these variants.
Jim G
Here you go:


and her's what it looks like with the rain cover on it:

It does significantly change the look, emphasizing the engine cylinders a lot more.
And for this hesitating because they fear this air cleaner will protrude more than a stock one:
I didn't have the stock one on long enough to measure it, but before I took off my Screamin Eagle synthetic filter which uses the stock cover, I measured the distance it protrudes from the engine. The measurement with the Extreme Billet air cleaner in place is IDENTICAL. It just LOOKS like it protrudes further, because it is smaller in horizontal width than the HD stock cover.
The hardest pat of making the swap was removing the old filter assembly. I SHOULD have checked the service manual first, because it turns out that the bolts have to be removed in a certain order, with the big ones holding the air cleaner AND throttle body to the cylinders LAST. If you remove them first, you;ll have to reinstall them to prevent the entire throttle body assembly from trying to move while you break loose the other smaller bolts (several of them!).
Then ,when mounting the new filter assembly, the trick is to put the s.s. screen into the billet cover with the slight bulge facing OUTward, so that it stays on the circular retainer ridge while you gently guide the billet piece plus screen into position over the filter element, and ensure that the gap between the filter edge and the billet piece edge is identical all the way around. You then tighten the center bolt, and then snap in the medallion.
Oh, and be sure to PRE-coat the bolts with blue loctite. That is critical. So is the torque on the bolts. Too loose, and the assembly will vibrate off the engine. Too tight, and you'll crush the air filter a bit. I used a Snap On torque wrench set to the precise torque and STILL slightly crushed the air filter, but so did the mechanic who installed the Scream in Eagle synthetic, and HE is a MASTER technician, so I figure HD just made the torque setting a bit high to ensure that the filter doesn't fall off the bike on the highway.
I like the end result a lot.
And, I intend to use the rain cover when it rains.
Jim G
Probably not helpful but it's my .02 cents! Good luck with your decision!
Probably not helpful but it's my .02 cents! Good luck with your decision!
I think filters that are able to draw COOLER air, i.e. from outside the area right beside the hot heads and cylinders, will produce more power. That's why the "Heavy Breather" is positioned where it is.
If I wanted the best performance, and nothing else mattered, I'd have gone with a Heavy Breather. But, I personally prefer the appearance (shape and location) of the "Extreme Billet" type. By going with the Extreme Billet, I acknowledge that I am drawing in hotter air than the Heavy Breather, but cooler than the regular Screamin' Eagle filter.
On my last bike though, a Honda VTX 1800cc watercooled V-twin, I had the Heavy Breather type because I got a fantastic deal on one versus anything else. An interesting thing happened there. It came with a good sized filter, but I was curious whether a larger filter would add a bit more power. So, I bought the largest filter that K&N offers, that would fit in the space I had to work with. The larger filter added 2 hp at peak rpm, and that 2 hp was reproducible whenw e repeated the comparison.
I don't know whether the larger filter did better because it was longer, or because it was able to draw air from even further from the engine by virtue of its longer length, or both, but the 2hp improvement is proof that the bigger filter DID make a difference.
Note also that the Honda was watercooled, so the heads and cylinders did not radiate heat anything like a Harley does. So, on a Harley, I imagine the beneficial effect of the larger/longer filter would be greater.
Jim G
- In stop and go traffic, where it makes an already bad situation for any Harley even worse
- During dyno tuning, where the heat is not effectively "blown away" by the typical fans used in an HD dealer dyno room, and thus adversely affects the tuning process. I have heard techs telling customers that they routinely temporarily suspend the tuning process whenever the engine gets a bit too hot, and let it cool.
Jim G
The Best of Harley-Davidson for Lifelong Riders
- In stop and go traffic, where it makes an already bad situation for any Harley even worse
- During dyno tuning, where the heat is not effectively "blown away" by the typical fans used in an HD dealer dyno room, and thus adversely affects the tuning process. I have heard techs telling customers that they routinely temporarily suspend the tuning process whenever the engine gets a bit too hot, and let it cool.
Jim G






