Bonneville America Forums Forums Technical Forums Performance Mods K&N High Flow Air Filter

Two years ago, Gary James and I opted for the poor man's Freak by drilling out three quarter-sized holes in the bottom of our air box and then three corresponding holes in the stock paper filters. With good results although we did kind of take a beating from some fans of the Freak. Nevertheless, I was happy with the results.

So here's a question for A. Those who did the same thing and B. Have now switched up to the better breathing K&N filter. Since it is suppposed to be a better breathing filter, did you drill out this one as well?

I realize this voids the warrantee but I'm sure the filter will still work. The only question really is will that be sending TOO much air through? I'm not a mech. My level of skill is barely beyond the "bolting sh*t on" stage, so I'm turning again to those who know more about these things than I. Thanks for the help.

BB

It may be "too much" for the jetting you have in there, but not too much overall. May need to tweak the jets and screws, but that's about it. That being said I have no idea cause I never did it

Oh...just what we need. TWO people who don't know how deep the water is diving in headfirst to find out.

BB

Let's make it 3...
A. I had the K&N for awhile, never drilled it. Due to an extremely dusty work environment, I went back to the stock filter.

B. Even though the K&N is supposed to flow more air, it can only flow what you give it, up to the limit that the engine can take in. ( airbox restiction and pipes - inflow/outgo).
Drilling it would allow more air in.
The crux of the biscuit is how did it run before, how does it run now, and what do your plugs indicate?

Hey...!!! Where'd you get the cool smiley of a teacher going through their daily routine? And can I get one?

BB

Don,
With the paper filter in there now and the Unifilter previously my plugs looked ok. I could simply drop the new one in and see how it runs and if I want I can drill out later. Actually as far as the plugs go, the only real way to tell is to find someplace to cut the engine and coast to a stop since the downshifting and difference in fuel / air flow and all that can change the way the plugs look. I've never actually done that. And, since I use the Lucas gas treatment every other tank or so which makes it burn hotter, it's a little hard to tell. But...I've never pulled my plugs and found them soaked and black or bright white so I'm guessing I'm in the range somewhere.

BB

Right clicky clicky.

I'm glad I have tons of unused bandwidth.

BB,I thought of drilling my KN filter and airbox out but noticed the KN doesn't have foam around the bottom to seal against the bottom of the airbox so air can get around that part of the filter. would have to come up with an alternative way to seal air from getting by. I too would like to know first hand if air box mods actually make that big of a difference for normal driving or just at high rpms.


mike

Please read this nice test...
http://www.bobistheoilguy.com/airfilter/airtest1.htm

With K&N your engine becomes a s%it sucker!!!

The best filter is the stock or a good paper filter when new.
But the paper filter become dirty soon, you can spry with air once or twice but before one year of continuous use you've to change it.

The better filtering/performance balance filter is the UNI foam filter. Keep clean and oiled and it's the cheapest and better for your engine life.

all I can say is that I did the uni filter and air box drilling with snorkel removal, then put in TBS needles with a shim and 130 mains. For me the bike is running like a top, smooth and I believe a good deal more powerful. I haven't had a dyno and the bike has never broken down or run that rough but I did need to adjust the pilots where I got the thumbscrew arrangements from Brent and found after several goes that 2 & 3/4 turns spot on. Still fiddling though and found the plugs really almost white initially but after adjusting the pilots they have come back to grey.

Staffo, how do you ride? hard and fast? high rpm on hwy or what I'm looking for is when do you notice the difference on your mods. power out of the hole? passing ability or pulling hills with 2 up?



mike

for a start I don't do much 2 up but when I do, my little women doesn't make too much diff to anything. Regards how I ride, mostly commuting to work however we have a good road network and not many cops around and only speed cameras and we know where the traps are. Anyway, that means my riding is along good stretches and I can get my bike up to 140kph really quickly when being bad staffo. I don't do enough highway work (who does) but as far as power, I find my bike is good throughout the whole spectrum. After my mods, all I had to do was make sure the pilot screw was adjusted right. For instance for some reason at 3 turns, I was running a bit too rich I think so I'm now at 2 and 3/4 turns out. I've just looked at my plugs and I think I still might be too rich so might now go to 2 and a 1/2 turns out. Apparently looking at various sites confirms my setup is good at 2 1/2. Anyway, that was my only problem where from idle up to 1/4 or so the bike was a bit rough but adjusting back has made a big diff. I also noticed my fuel consumption suffered until i screwed the idle pilot mixture screw in. The rest of the band is really strong.