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So, the bike (05 KDX220) I just bought had the airbox lid removed and the box and filter were full of dust. Buddy gave me the lid, I assume he removed it for better airflow.

I did think this bike ran much better than my last 220, but that could be for a myriad of reasons.

The engineer in me thinks opening the box wide open to dirt and water is a bad thing, so I reinstalled it.

Opinions? Experiences? Thanks!

Removing the airbox lid is generally considered a performance enhancement.

All mine have been removed.

There's other options to get the same result

what about a reliability inhibitor? i.e. when you ride in the rain or puddles or mud and suck in water.

Has anyone fubared their engine with an open airbox lid?

if you keep your air filter clean, shouldn't be an issue, unless you like to use your bike as a submarine

I run mine without the lid and no problems so far. Of course, I live in the desert so there are not a whole lot of opportunities to drown my bike. Remember, dirt in the air box is not a problem. Dirt past your air cleaner is.

Buy one of those airbox washing covers, so that during cleaning you can just pull the seat off and pressure wash the inside of the airbox squeaky clean everytime!

my 03 220 never really liked the airbox lid removed (even after i re-jetted it ripped on wide open throttle but i lost some of the bottom end grunt)...instead i just removed the snorkle & leaned off the jetting now it pulls strong in every gear, & sounds much better too..i cut the foot off a pair of the girlfriends old tights & slip that over the air filter in dusty or muddy conditions, then remove it when it gets a dirty...the air filter remains clean & wont need cleaning for several more rides. .helpful tip!

I have always wondered if the louder intake noise makes people think it makes more power. Not sure it can be explained by increased airflow, since the C/S area of the snorkle opening is larger than the carb throat diameter.

I've never used the airbox lid on mine, no problems yet (almost 2 years). Looks to me like if your riding in dusty enough conditions to get a layer in the airbox, it would do it with the lid or without. Same for getting water in the motor. Submerge it with the motor running, and it's going to fill it with water even with the lid on it.
Just keep the filter cleaned, and it'll all be good.

Personally I didn't notice much of a power increase on our stock KDX when removing the air box lid. This was tested when I was jetting the bike and trying different combinations. This is not too say that it didn't add some power, but on a stock bike with only a pipe and silencer change it wasn't dramatic.

As far as reliability, I wouldn't worry about it, most MX bikes come from the factory with an open airbox. As mentioned, keep the filter clean and well oiled and you will be fine with the lid removed. As far as water goes, this would mean you were seat deep in water, right? I think at that point you are awful close to filling the exhaust with water too, so what's the difference.

My .02 worth

thanks guys.

as for water - I'm thinking monsoon downpours that we sometimes get stuck in the forest with in Vancouver (aka raincouver)

Personally I didn't notice much of a power increase on our stock KDX when removing the air box lid. This was tested when I was jetting the bike and trying different combinations. This is not too say that it didn't add some power, but on a stock bike with only a pipe and silencer change it wasn't dramatic.

As far as reliability, I wouldn't worry about it, most MX bikes come from the factory with an open airbox. As mentioned, keep the filter clean and well oiled and you will be fine with the lid removed. As far as water goes, this would mean you were seat deep in water, right? I think at that point you are awful close to filling the exhaust with water too, so what's the difference.

My .02 worth

I second this. If you do the calculations of the flow area of the snorkle. It's easily 20%+ bigger than the flow area of the Throttle body. I added 2 more 1" "snorkels" with PVC elbows (function exactly like stock snorkle) just for peace of mind.
I think the perceived power increase is the same reason why 95HP honda owners think the intake made their rides faster...it adds a fair bit of sound/throatyness to the motor.

My additional .02 worth :)

Main (only) thing I miss the airbox lid for.. it was a good place to mount the little rectifier thing.
Got it screwed to the inside of the box now, but it's a PITA having to take it off to change the air filter.
Need to look for another place to put it I guess.

That little rectifier thing is really the CDI box.

my bike's previous owner had the CDI box zip tied firmly to the frame on the left of the air box. Nicely out of the way.

so, FWIW, i've decided to go with no snorkle, but keeping the lid.

heckler wrote:my bike's previous owner had the CDI box zip tied firmly to the frame on the left of the air box. Nicely out of the way.

I'll have a look at doing something like that too.
Thanks

OLHILLBILLY wrote:

heckler wrote:my bike's previous owner had the CDI box zip tied firmly to the frame on the left of the air box. Nicely out of the way.

I'll have a look at doing something like that too.
Thanks

+1 That's where mine is and it stays put.