Holes in the airbox

DJL219
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DJL219
Edited Date/Time 8/6/2022 1:23pm
I have a 2022 CRF250R and was thinking about drilling some holes in the airbox side plate similar to how the HRC boys do it. Who has done it? Is it worth it? How much dirtier does the airbox get? Any helpful tips, horror stories, or any more info are much appreciated. Thanks!

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Dirt.Squirt
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Dirt.Squirt 8/2/2022 7:22pm
8/2/2022 7:22pm
Crazy how you pay 10kish for a bike and “have” to take a hole saw to the bitch to make it run to its best ability
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Meister
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Meister 8/2/2022 7:41pm
8/2/2022 7:41pm
I can't stand how fast it gets dirty now so I'm definitely not drilling holes.
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LouisianaMotocross 8/2/2022 7:59pm
8/2/2022 7:59pm
Dirt.Squirt wrote:
Crazy how you pay 10kish for a bike and “have” to take a hole saw to the bitch to make it run to its best ability
It’s crazy you think the manufacturers are trying to get the bike to run to the best of its ability. They have to consider much more than just performance for a production bike.
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zehn
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zehn 8/2/2022 8:06pm
8/2/2022 8:06pm
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Joshracing 8/2/2022 10:51pm
8/2/2022 10:51pm Edited Date/Time 8/3/2022 1:15am
Meister wrote:
I can't stand how fast it gets dirty now so I'm definitely not drilling holes.
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more often, while enjoying maximum performance, that's where some guys gain the advantage. If top racers are doing it, clearly it works.

Make sure to hit the 'downvote' button, as performance is not really what you're after!
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Bruce372
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Bruce372 8/2/2022 11:24pm
8/2/2022 11:24pm
Years ago, headaches were treated by drilling holes in people's skulls because they thought it would let the demons out.

So let the demons out of your engine
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Joshracing 8/2/2022 11:26pm
8/2/2022 11:26pm
Bruce372 wrote:
Years ago, headaches were treated by drilling holes in people's skulls because they thought it would let the demons out. So let the demons out of...
Years ago, headaches were treated by drilling holes in people's skulls because they thought it would let the demons out.

So let the demons out of your engine
In think they still actually do this in some emergency cases.... Not for demons though!!!
luke11
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luke11 8/3/2022 1:52am
8/3/2022 1:52am
Meister wrote:
I can't stand how fast it gets dirty now so I'm definitely not drilling holes.
Joshracing wrote:
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more...
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more often, while enjoying maximum performance, that's where some guys gain the advantage. If top racers are doing it, clearly it works.

Make sure to hit the 'downvote' button, as performance is not really what you're after!
Don’t know why the downvotes you’re right.
I wash and replace my air filter after every single ride but seems like a lot of Americans don’t. I’m presuming because you use new pre-oiled filters everytime that costs $. Don’t understand why you wouldn’t just wash and re-oil. I can get through a whole years riding with 2-3 filters in rotation.
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Joshracing 8/3/2022 5:56am
8/3/2022 5:56am
Meister wrote:
I can't stand how fast it gets dirty now so I'm definitely not drilling holes.
Joshracing wrote:
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more...
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more often, while enjoying maximum performance, that's where some guys gain the advantage. If top racers are doing it, clearly it works.

Make sure to hit the 'downvote' button, as performance is not really what you're after!
luke11 wrote:
Don’t know why the downvotes you’re right. I wash and replace my air filter after every single ride but seems like a lot of Americans don’t...
Don’t know why the downvotes you’re right.
I wash and replace my air filter after every single ride but seems like a lot of Americans don’t. I’m presuming because you use new pre-oiled filters everytime that costs $. Don’t understand why you wouldn’t just wash and re-oil. I can get through a whole years riding with 2-3 filters in rotation.
Exactly right. Sort of makes you laugh thinking, "my filter gets dirty, let's plug up all holes where dust can enter". We're in motocross, dust is everywhere. More dust in the airbox, comes with more air, which is the point! If the top guys are using vented airboxes, pay attention to where they use them, which events, altitude, track conditions. Make a note of it. Makes sense to me.
Please downvote to show approval!
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KiwiBermRailer 8/3/2022 6:15am
8/3/2022 6:15am
I use to drill my hand guards out like the pros?! Use to get more airflow to my hands. Really helped….. oh and it let stones though.
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swordfish
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swordfish 8/3/2022 6:23am
8/3/2022 6:23am
Meister wrote:
I can't stand how fast it gets dirty now so I'm definitely not drilling holes.
Joshracing wrote:
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more...
Don't you think that it getting 'more dirty' means it's actually working? As a racer, you're after maximum performance, if it means washing your filter more often, while enjoying maximum performance, that's where some guys gain the advantage. If top racers are doing it, clearly it works.

Make sure to hit the 'downvote' button, as performance is not really what you're after!
luke11 wrote:
Don’t know why the downvotes you’re right. I wash and replace my air filter after every single ride but seems like a lot of Americans don’t...
Don’t know why the downvotes you’re right.
I wash and replace my air filter after every single ride but seems like a lot of Americans don’t. I’m presuming because you use new pre-oiled filters everytime that costs $. Don’t understand why you wouldn’t just wash and re-oil. I can get through a whole years riding with 2-3 filters in rotation.
Why would you change something that doesn’t need to be changed? Waste of time and money if the filter is not saturated and still filters and works fine.
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TeamGreen
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TeamGreen 8/3/2022 8:06am
8/3/2022 8:06am Edited Date/Time 8/3/2022 4:01pm
Recently drag raced my stock engined Honda Off-Roader/CRF450X(Twisted Development Vortex/Yosh pipe/stock airbox, filter, cage & cover with snorkel installed) against a Honda Race Team prepped & modded CRF450X (RX ECU/Cam/airbox cover removed/team pipe…etc.).
We drag raced down the beach in Baja…all 6 gears.
The bike with less mods and the completely stock airbox/filter system won. Grinning

I’ve left my air-box stock for off-road reasons…like water crossing…etc (yes, I’ve put water thru an engine…or two!).

On a motocross bike, I’ve seen air box mods for decades and plenty of engine builders say it works.
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mxav8r
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mxav8r 8/3/2022 8:26am
8/3/2022 8:26am Edited Date/Time 8/3/2022 8:27am
In a video about this bike (I think Dirt Bike or MXA) the mechanic said they add the holes for additional airflow due to all the data/electronic equipment located inside.

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mxav8r
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mxav8r 8/3/2022 8:30am
8/3/2022 8:30am
You would be surprised at the "stuff" Factory Teams have hiding underneath/behind the seat and panels...


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mikebrownsound 8/3/2022 12:36pm
8/3/2022 12:36pm
There is a difference for them drilling holes for their engine application, so yeah there is a reason for it. Not sure the average weekend warrior would benefit of drilling holes. Not that it would harm anything. But yeah you need to cover it up everytime you wash the bike.

Keefer did it on the (husky/ktm) wich seems to be beneficial, qouting him: 5. Airbox Mod: You want a little more excitement out of your Husqvarna’s low end? Drill some 1/2 inch holes in the left side airbox cover (as shown) and you’ll get some increased throttle response throughout the RPM range.
Mucktub
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Mucktub 8/3/2022 12:53pm
8/3/2022 12:53pm
mxav8r wrote:
You would be surprised at the "stuff" Factory Teams have hiding underneath/behind the seat and panels... [img]https://p.vitalmx.com/photos/forums/2022/08/03/562480/s1200_evo5HRC.jpg[/img]
You would be surprised at the "stuff" Factory Teams have hiding underneath/behind the seat and panels...


Looks like a dirty mark on that filter, better change it to keep up the performance.
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lostboy819
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lostboy819 8/3/2022 12:56pm
8/3/2022 12:56pm
DJL219 wrote:
I have a 2022 CRF250R and was thinking about drilling some holes in the airbox side plate similar to how the HRC boys do it. Who...
I have a 2022 CRF250R and was thinking about drilling some holes in the airbox side plate similar to how the HRC boys do it. Who has done it? Is it worth it? How much dirtier does the airbox get? Any helpful tips, horror stories, or any more info are much appreciated. Thanks!

Why don't you just cut out some small circles out of black back ground material and then you can stick them on to look cool but not get any more dirt into the airbox. Wink
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LungButter
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LungButter 8/3/2022 1:05pm
8/3/2022 1:05pm
luke11 wrote:
Don’t know why the downvotes you’re right. I wash and replace my air filter after every single ride but seems like a lot of Americans don’t...
Don’t know why the downvotes you’re right.
I wash and replace my air filter after every single ride but seems like a lot of Americans don’t. I’m presuming because you use new pre-oiled filters everytime that costs $. Don’t understand why you wouldn’t just wash and re-oil. I can get through a whole years riding with 2-3 filters in rotation.
I'm presuming you also understand that it costs money every time you clean and oil it right?

Drill away boys, I'm sure those air box holes are the final piece of the puzzle to finally help you lock down the Vet C Title at BFE Raceway
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GG121
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GG121 8/4/2022 5:21am
8/4/2022 5:21am
Read any review of a Gasgas and they always mentioned that it has less power than a KTM, and that's because the KTM has a highly vented airbox cover. Nowadays it seems most factory teams that drill it leave the holes open, but in the past I remember teams would cover the holes with foam, from the density it looked like skid plate foam. Also Ive heard teams put tape sticky side up inside the airbox to catch flying dust.
DiddyDaddy
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DiddyDaddy 8/4/2022 6:57am
8/4/2022 6:57am
i was at a hill climb race for the first time a few weeks back and all those guys took off there air box side plate. one of the first things i noticed.
i would say holes would have to help and if you change your filter after ever ride then i dont see a problem. maybe have a another side plate on hand incase riding in bad conditions. or be getto and apply duck tape hahah
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AngryBear
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AngryBear 8/4/2022 7:35am
8/4/2022 7:35am
GG121 wrote:
Read any review of a Gasgas and they always mentioned that it has less power than a KTM, and that's because the KTM has a highly...
Read any review of a Gasgas and they always mentioned that it has less power than a KTM, and that's because the KTM has a highly vented airbox cover. Nowadays it seems most factory teams that drill it leave the holes open, but in the past I remember teams would cover the holes with foam, from the density it looked like skid plate foam. Also Ive heard teams put tape sticky side up inside the airbox to catch flying dust.
same with husky for many years. the subframe design was much more restrictive, way more choked down compared to it's orange brother
Tumic
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Tumic 8/4/2022 12:16pm
8/4/2022 12:16pm
I had a crf250 on the dyno around 2015. It had a high comp piston, cam, ported head, vortex ecu and a exhaust done to it.

When i removed the seat as a test, it made 1hp extra on the dyno. I then removed the airfilter and that did nothing.

So i ended up going home and drilling a couple of 1hp holes in my airbox, the cheapest 1HP ever found.

The Akrapovic exhaust made 2HP and cost like 1200$, the wholes were free and made half the power of the exhaust.

Now, would it have been 1hp on a stock engine? I doubt it, but on a race engine it ended up being that way.

And No, im not Jett Lawrence either, but free HP is free hp..
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AMDnutt
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AMDnutt 8/4/2022 1:00pm
8/4/2022 1:00pm
This was a big thing in the late 70's and all through the 80's. Especially with the dual sided airbox of the RM's in the early 80's. Drill some 1" holes and rejet to get things tweaked. Did it myself on most of my bikes back then.

The above posted "Old school airbox breathers" was an option a few people used but I always just used screen mesh to cover them and keep out the larger debri...


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AMDnutt
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AMDnutt 8/4/2022 1:01pm
8/4/2022 1:01pm
FYI - Not my bike in the pic above, copied from other post
AMDnutt
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AMDnutt 8/4/2022 1:02pm
8/4/2022 1:02pm
Twin Air had the hot set up though...

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captmoto
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captmoto 8/6/2022 1:23pm
8/6/2022 1:23pm Edited Date/Time 8/6/2022 1:23pm
luke11 wrote:
Don’t know why the downvotes you’re right. I wash and replace my air filter after every single ride but seems like a lot of Americans don’t...
Don’t know why the downvotes you’re right.
I wash and replace my air filter after every single ride but seems like a lot of Americans don’t. I’m presuming because you use new pre-oiled filters everytime that costs $. Don’t understand why you wouldn’t just wash and re-oil. I can get through a whole years riding with 2-3 filters in rotation.
Because they don't need it. It's just some people got it in their heads that they and their bike will die a horrible death if they don't change their filter every ride and their oil every moto.
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Dirtdemon 2/11/2024 1:42am
2/11/2024 1:42am

Do ecu sense more air and delivers more fuel ?
Or do you need to remap ? buy vortex ?

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