How to make neat holes in airbox?

[Strong Bad]

Step drill makes a nice round hole.

[rapidoxidationman]

Pic a size and aim well:



Gotta say I'm in the camp of "the engineers knew what they were doing" though.

[JimVonBaden]

Hole saw.

As for the legitimacy of doing it, it just depends. The engineers, as mentioned, design an airbox for a wide variety of factors. Noise is a big one.

On my Triumph Scrambler, the airbox mod really helped with an open exhaust.

Jim

[yankeeone]

I would try a new
forsner bit , cuts a nice clean hole.

[bomber60015]

Originally Posted by yankeeone

I would try a new
forsner bit , cuts a nice clean hole.

Forstner bits work great, but are happiest in a drill press . . . ..

[H96669]

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.

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.

[sailah]

Pick up a deburring tool, cleans the fuzz from the drill bit like magic

[geometrician]

Originally Posted by sailah

Pick up a deburring tool, cleans the fuzz from the drill bit like magic

+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...

[anonny]

My vote is with the step bit too. Forestner wood bit will made a nice clen hole as well if you have one.

[Ricardo Kuhn]

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.

[Colemanfu]

Depending on the number and size of said holes, perhaps a re-jet as well.

[Range Motorsport]

Originally Posted by It'sNotTheBike

Probably because the OP imagines the trained engineers who designed the air intake
botched the job, though those engineers had access to a dyno and more than likely spent
many hours making sure the airflow was optimized for the resonant cavity of the air box,
( think of Helmholtz and you will be on the right track).


How likely is it that the engineers did a bad job and someone who needs to ask how
best to cut holes in the air box will do a better job ? Sort of like leaving an orangutang
in front of a typewriter and waiting for the sonnets of Shakespeare to be produced
( don't hold your breath waiting for anything intelligible to come out of that typewriter ).




.

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.

[troidus]

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?

[t6pilot]

Unibit/step drill
Use a marker on the bit at the diameter you want

[1P8RIOT]

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. 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.