Holes in side cover for more power?

What got me to thinking about it is the other night I was riding home in frigid temperatures with jeans on. Freezing my ass off. I crouched way down to get behind my tiny wind screen and my leg was on that side cover. That thing buzzes and pulses like crazy at speed. Feels like touching a speaker cone thats hitting hard. Must mean the power pulses are pulling it back and forth right? Meaning it would breathe easier with holes in it? What about the sound though? On the one hand it would be louder because you could hear the intake, but how much noise does the side panel pulsing like a speaker cone cause?

Holes will = more noise
Holes will = more dirt into airbox
Holes will = easy access for water to get into airbox

Holes should equal more power


You decide if it's worth it.

The plan was a pre filter filtering the air coming in the holes so that should stop the dust and water. The big question for me though is how much louder will it get. I'm trying to quiet the bike down right now. Just bought a quiet core insert.

You want quieter, put the airbox door back on and don't put holes in side cover or airbox door.

Uni-filters in holes would probably not add to much increase in noise, but I don't know anyone who has done that.
But I would assume it would be at least a touch louder.

You mean like this:

https://wr250rforum.forumotion.com/t3843-another-airbox-mod-thread?highlight=airbox

Looks like a good mod to me!

Still as motokid says, you have to decide what you want. For a small bore 4T there is nothing cheaper than open airbox/exhaust for extra horsepower.

One thing you don't want to do is use a K&N filter if you are riding offroad/dusty conditions. K&N filters are the best flowing filter for street applications but clog up quickly in the dirt.

ballisticexchris wrote:

You mean like this:

https://wr250rforum.forumotion.com/t3843-another-airbox-mod-thread?highlight=airbox

Looks like a good mod to me!

Still as motokid says, you have to decide what you want. For a small bore 4T there is nothing cheaper than open airbox/exhaust for extra horsepower.

One thing you don't want to do is use a K&N filter if you are riding offroad/dusty conditions. K&N filters are the best flowing filter for street applications but clog up quickly in the dirt.

That's uni-vents in the airbox door.

OP has removed airbox door completely and is questioning putting holes, and possibly filtered vents in the side panel that goes over the airbox door.

I did see a pic somewhere of a race prepped white wr250x i guess from japan....
It had holes drilled in the sidecover with air-vents installed. 4 or 6 of them i think.
Looked really nice so i was also thinking of doing that because i have some vents at home allready.

I have also felt that the sidecover is "pulsing" when u ride the bike... so i understand what u talking about.

This was a lot more difficult and time consuming than I thought it would be. Took forever to get rid of all the messy stringy lip area around both sides of the holes and that foam insulation was really on there.

Also note the lack of chicken strips on the Shinko 705s. They really arent that bad once they are good and worn in and you are used to them. Still heavy and make the bike less responsive, but they grip and you learn to compensate. When I finally put lighter, smaller, better, tires on it though... I will probably be so used to compensating ill probably wreck from using too much body language.

oic0 wrote:

This was a lot more difficult and time consuming than I thought it would be. Took forever to get rid of all the messy stringy lip area around both sides of the holes and that foam insulation was really on there.

So what's the verdict on noise?
What about performance?
What's your method of filtering or are they just straight holes into open airbox?

Louder? yes. Has more blat to it. The exhaust goes thump thump, the intake goes blat blat. Perhaps not a bad thing. They say loud pipes save lives, well the pipe makes sound behind me. Those arent the people who don't see me. Its the people im running along side of or that I'm approaching from behind. Maybe some sound out to the sides isn't so bad.

More power? I'm not sure but it feels flat now. I think I need to up the fuel settings a touch. Also, the being louder means I use less throttle because I don't like being obnoxious on my commute. That may be some of it. Hopefully the quiet core insert takes a bite out of the overall sound despite the holes.

Holes are straight through at the moment. I plan to put either a square of prefilter or some pantyhose behind it to keep it from sucking rain in. I occasionally get caught in a down pour.

Update: With the new air filter that has no mesh screen and having the jetting increased slightly across the board... I can't tell if it has faster acceleration, my butt just isn't that accurate, I will say it pulls better at mid speeds in 6th gear. Going from say 47mph up to 60mph in 6th doesn't give as much of a "I need to down shift" vibe (*note, my gearing is higher than stock because of tire height). I'm not quick to give either mod credit though, I could have just been a touch too lean before and my other air filter had 4000 miles of dirt and dust in it (there isn't much dust in Louisiana).

*Update, to my Update*
Some ol fat lady turned left in front of me at an intersection. Soon as she went by I pinned it out of anger (1st gear). It carried the front wheel about 1ft off the ground through the whole intersection with my 275lbs crowding the bars and leaning forward. I was just riding how I always do. Its not uncommon for me to pin it for no particular reason. Thats the first time that its brought the wheel up that high or kept it up when not riding down a hill or scooting back a bit and tugging. Something I did gave it more oomph. It was one of those didn't expect it wheelies like I get on my KX500 in 1st through 3rd. Thats what makes a dirt bike feel like a dirt bike to me. Those oh shit! wheelies. Now if only it had enough oomph and was light enough to do em in at least 2nd gear too