The noise thing....that can be very annoying depending on exactly what kind of noises you create. Could be good noises but sure wasn't so on my snowmobile back then. Seemed to come up at high pitch and into my helmet.:huh I replugged them holes. And I am getting old and hearing going down. May have something to do with all them moving air noises at work.:eek1
+1 you just gotta have one in your toolbox- they work wonders on metal & plastic. A simple self-aligning tool that a file can't quite replicate. And inexpensive. You can start with a small hole and easily increase it with the tool (once you cut a hole you no longer have a center for the bigger hole saw to align on) and can make custom-shaped holes to match the contours of the box, frame position, etc I use the General Tool No 482 deburring tool, can be found at Home Depot, Lowes, etc as well as good hardware/hobby shops: intake noise & weatherproofness are the deciding factors. The engineers design on noise, filtering, ease of maintenance, rain-proofing. But now, mostly intake noise. If someone modifies their engines (carb, cams, exhaust) they could certainly increase performance/power, I'm one of many who have done it- often at the sake of rain-proofness. To each his own...
My vote is with the step bit too. Forestner wood bit will made a nice clen hole as well if you have one.
Regardless of been a good idea or not, like making holes on a piece of plastic just for fun.. You can use stainless steel mesh like this and some pop rivets to add effect.
You are right no one has ever removed or modified or redesigned an airbox and made more power... Just like exhausts, fuel maps, and head porting do nothing for performance. You can also take any bike off the showroom and race it because they engineered it to be the fastest most efficient bike from the factory.
Bigger isn't always better. Some older heads respond well to filling the floor of the intake port to reduce volume and increase velocity and increasing the radius of the turn into the valve bowl to reduce fuel separation. On the Concours, there is an airbox mod that involves reducing the area of the intake for a boost in performance, but there needs to be a corresponding jet change or it goes rich. You have to decide, when making mods, if you want every last bit of power wrung out above 9,000 at the expense of having an otherwise unrideable bike, or if you want to increase usable power in the middle of the rpm band where you spend most of your time. Are most of your trips a quarter-mile, 14 miles, or 1400 miles?
On my F800 I used a hole saw to put 3 holes on the part of the air box that's above the filter. I think the holes are 1" maybe 1 1/4" Before I did this I thought about what would happen if i wasn't happy with it. The plastic part I drilled into cost lass than $10.:eek1 A BMW part that's only $10??? I figured it was worth 10 bucks to see if the mod that had worked on everything else I'd ever owned would work on this. I noticed better bottom end/low speed response and no negative results(same top end, mileage etc.) I do hear a little more engine noise but it's nothing.
I just gutted my whole air box. If you aren't worried about off road, pod filter it and jet/tune for it. The engineers knew best? Bah! The federal government designed the friggin intake and exhaust!
The goals of the engineers might differ from the goal of the OP. It is possible to tune the same engine differently to get different characteristics. I'm not saying going around drilling random holes in things is the way to go, but if you can manage to shove more air and fuel into an engine in the correct mixture, you will get a bigger boom and more power. Whether or not this produces undesired results by way of reduction of fuel economy, airbox noise, etc... is irrelevant; none of those things are (hopefully) the goal of the OP. On the dyno comment, you do realize that the reason most people cut holes in their airbox is that they've purchased a jetting kit which requires larger airbox holes work properly? Most companies who make these kits such Dynojet or JD, also have access to dynos, and their results against the stock power curves can be seen. Anyway, to answer the OP's original question, use a holesaw to cut out the corners then use a heated razor blade to cut nice straight lines between the holes. Optional is some sort of sanding wheel for cleanup after. You can see it illustrated here on a DRZ400S https://www.youtube.com/watch?v=VtKWbs0N5lo
Nice "effects" but I have never seen that screen in SS.I could use some. I sure have quite a bit of that in Aluminium, some of the old satellite dishes were made of it. Works great with Devcon for roadside repairs.
I prefer a step bit. But if you use a hole saw run the drill in reverse for a cleaner hole. It takes longer because its not as aggressive.
Hole saw works best, deburr with a Burr-Kwik sheet metal deburring tool. SOUND is the biggest compromise in airboxes. Intake noise can be louder than exhaust. I'm with the "keep it intact as designed" group.
BTW making holes in the lid on the outside of the filter doesn't change the Hemholtz. But it does move the anti-resonance. Tread lightly.
