There are a variety of intakes and air cleaners that claim to be so much better than stock. Move more air, better flow, and you name it for claims. But I haven't see any real numbers how much better an aftermarket, or even a HD "upgrade" is in reference to stock. Yes on my bikes, 2 touring and the Fatboy, I did upgrade, made pipe changes and muffler changes. Also used different fuel programmers. I figure that for the touring bikes when I replaced the head pipes, the extra potential airflow and a tuner was necessary to help it run cooler to try to get some of that twin cam heat away. The Fatboy got new mufflers since that's where the cat is but with just that changed I'm not sure about the wisdom or benefits of a different intake or tuner. Personally I'm not convinced or claims made by K&N and especially claims made by an unsuspecting customer who raves over it. Lots of myths out there. Example the dirtier it gets the better it gets/filters. BS

When I replaced the air cleaners on the bikes I compared the orifices and frankly didn't see any enlargement. Filter elements were different shape but there was no claim about how much, if any, larger in surface are the element was.

 

Think of it more as increasing the efficiency of your bike rather than just flowing more air. Internal combustion engines are pretty inefficient in design and there are a ton of factors that can increase or decrease your starting point. Intake is one of the easiest and cheapest to do. An open element K&N has the potential to flow significantly more air than the stock HD intake. But there will be a limit to how much air your engine can handle. So if you upgrade anything in the engine (displacement, timing, head work) then you absolutely should upgrade the intake to take be able to take advantage.

If you just upgrade the intake on a fairly stock bike, you won't see much difference since the engine is already operating towards it's max efficiency. You'll probably get better throttle response, but not much else unless you do something to the engine to take advantage of the upgraded air flow.

 

I've done the intake and slip on mod on just about every bike I have owned. To be honest I don't think it makes a big difference in performance. Maybe adds another 5 HP or so I guess. I do notice throttle response often improves and if the bike is tuned properly engine heat decreases.
I doubt anyone is going to be breaking any land speed records just from adding a high flow filter and a set of slip ons.

 

With the touring bikes, one of the objectives was reduce heat. Basically a package of intake, headpiece and mufflers to compliment each other. On all them I rode for 1K miles before the changes and except for the cooler running, I didn't see any performance enhancement. No I didn't dyno it and yes that answer is subjective. On the Fatboy the changes, intake, tuner and mufflers were more "habit" that performance or cooling. Cat is in the mufflers so getting rid of that helped with cooling and the mufflers let me hear the engine. Figured that intake and tuner would be appropriate in that case. Didn't like the tuner, PC5 because it kept throwing an O2 code which was bogus because the O2 sensors were bypassed. Last week I pulled the thing and will put it on eBay or this site for sale. Maybe for someone else it will work well. Got it from Fuel Moto, talked several times to them about the issue and they sent replacement O2 Optimizers, basically a jumper plug, which usually only lasted a few weeks at best. Gave up, tired of trying to get a proper tune and pulled it. I may be selling or trading the Fatboy so I'm also De-modding it. No sense in giving away the improvements I made besides a lot of people don't want someone else personalization.

 

Oiled gauze air cleaners like K&N flow more air but they also flow more dirt. If I lived in a dusty climate, I wouldn't use one.

 

http://www.dkcustomproducts.com/blac...m#!prettyPhoto

FYI


I just picked one cleaner off the page. There are results for each set up they have
Click on the chart pic