Air Box Flapper Partial Removal?

I have been contemplating on doing the airbox flapper mod but had a few questions.

1. Can you just remove the hose off the air flapper actuator device (flaps the flapper and sits on air box) and just plug the hose instead of removing the controller (or whatever it's called) and hoses? I'd rather leave the stuff there so I can easily go back to stock if I ever sell the bike or just want to go back to stock quickly.

2. There is a video on youtube showing a guy using double-sided tape to hold down the flapper, is this a good method or should I just screw it down? If I screw it down will it put a hole in the air box?

3. When you remove the flapper actuator (or whatever it's called) that's on top of the air box it leaves a hole, do you recommend covering it with duct tape? I see some people just put their fuel controller on top but I'd rather keep my PC next to the battery.

4. I hear the flapper mod doesn't really do much and you'll get better performance by removing the air box door. If I remove the air box door, not permanently but rather just when I ride street, does anybody have setting for a PC for the Air box door removed +FMF Q4 exhaust + mega bomb header? I had planned on having the bike custom mapped on dyno but I don't want to get a custom map with the air box door removed because I will want the door on for off-roading to hel prevent water from getting in the air box should I eat water.

5. Has anyone removed the air box door and replaced it with screen to help reduce some dirt from entering the air box? Just a thought.

Just forget about the flapper and make a bigger opening if you want to go back to stock at some point.

If you like how it runs with the air box door removed(it makes more power at all rpms if tuned right so you will) cut a 2 x 2 or 3 x 3 inch hole in the air box right above the air filter, this gives you tons of air and keeps water out as good as possible for riding off road. You could also do this with a 1 inch hole saw making 4-6 holes, this way you could get rubber plugs (at a hardware store for electrical boxes) to seal them up if you ever wanted to go back to stock.

I have a 2 1/2 by 2 1/2 inch hole in the air box above the filter plus the ultimate air box mod(not enough air flow on its own IMO), water splashes into the stock opening before it gets in the new hole I cut, theres no need for you to change the air box back to stock for off road just cut the hole.

If you don't believe me go for a quick ride in some water then take the seat off and look at the air box, it will be clean in front of the stock opening/flapper junk right above the filter where I cut a hole and dirty around the stock opening.

Opening up the air box is just as important as adding the pipe if you want more power, doing one without doing the other doesn't add much power.

I taped up the hole the flapper actuator left on the top of my air box to help keep water out.

Biglake wrote:

Just forget about the flapper and make a bigger opening if you want to go back to stock at some point.

If you like how it runs with the air box door removed(it makes more power at all rpms if tuned right so you will) cut a 2 x 2 or 3 x 3 inch hole in the air box right above the air filter, this gives you tons of air and keeps water out as good as possible for riding off road. You could also do this with a 1 inch hole saw making 4-6 holes, this way you could get rubber plugs (at a hardware store for electrical boxes) to seal them up if you ever wanted to go back to stock.

I have a 2 1/2 by 2 1/2 inch hole in the air box above the filter plus the ultimate air box mod(not enough air flow on its own IMO), water splashes into the stock opening before it gets in the new hole I cut, theres no need for you to change the air box back to stock for off road just cut the hole.

If you don't believe me go for a quick ride in some water then take the seat off and look at the air box, it will be clean in front of the stock opening/flapper junk right above the filter where I cut a hole and dirty around the stock opening.

Opening up the air box is just as important as adding the pipe if you want more power, doing one without doing the other doesn't add much power.

I taped up the hole the flapper actuator left on the top of my air box to help keep water out.

Hey thanks for the reply! Would you have to have a picture of your cut out? I'm having trouble visualizing your description?
Didn't the original "ultimate air box mod" guy initially put a bunch of holes in the air box like you are describing only to end up buying another air box and doing his ultimate air box mod instead?

What I'm going to so is get a custom power commander map for the air box door removed and when I ever plan on dealing with water crossings to switch maps and put the door back on. I don't want to put any holes in the air box or modify the air box.

DS123 wrote:

Hey thanks for the reply! Would you have to have a picture of your cut out? I'm having trouble visualizing your description?
Didn't the original "ultimate air box mod" guy initially put a bunch of holes in the air box like you are describing only to end up buying another air box and doing his ultimate air box mod instead?

I don't know what that guy was smoking when he did that but he wasted a couple hp and a bunch of his time and money.
Water does not hit the top front part of the air box where he added holes, its the same location as the air box opening on pretty much every other dirt bike.
You cut/drill holes in front of the tip over switch, i'll take a pic of my air box tomorrow for you.

Biglake wrote:

DS123 wrote:

Hey thanks for the reply! Would you have to have a picture of your cut out? I'm having trouble visualizing your description?
Didn't the original "ultimate air box mod" guy initially put a bunch of holes in the air box like you are describing only to end up buying another air box and doing his ultimate air box mod instead?

I don't know what that guy was smoking when he did that but he wasted a couple hp and a bunch of his time and money.
Water does not hit the top front part of the air box where he added holes, its the same location as the air box opening on pretty much every other dirt bike.
You cut/drill holes in front of the tip over switch, i'll take a pic of my air box tomorrow for you.

Ok, I understand where now. The ultimate air box mod guy did exactly as you did but for some reason he thought it would be better to gut the internals instead.

Does anyone have a custom map for a FMF Q4 + megabomb + air box door removed? I'd rather avoid a custom dyno tune because these places around here take forever to do it.

Heres a picture.
I haven't had the seat off in a year so its dirty lol but this helps show where mud/water hits the air box.
I have strips of foam mat zip tied beside the stock opening to help keep mud/water out, as you can see most all of the dirt is around the stock opening with the extra hole above the filter being fairly clean.
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Yup I would say its time for a cleaning hahaha

thanks for the pic. Man it looks like you went riding in a dust storm. lol

Some rides I have to clean/change the air filter before I can ride it again, we ride on dusty fire roads and muddy sled/atv trails it fun but you and the bike get very dirty.

I can tell when my air filer is getting dirty, the bike loses bottom end tq, these bikes need lots of air to make more tq than stock off idle which is why I always recommend air box mods for any one with a pipe and programmer as its just as important for making power.

Biglake wrote:

Some rides I have to clean/change the air filter before I can ride it again, we ride on dusty fire roads and muddy sled/atv trails it fun but you and the bike get very dirty.

I can tell when my air filer is getting dirty, the bike loses bottom end tq, these bikes need lots of air to make more tq than stock off idle which is why I always recommend air box mods for any one with a pipe and programmer as its just as important for making power.

What if I remove the air box door and put a sheet of that foam filter in place of the door, use velcro to hold it on and remove it when I want to clean the filter? That way any loose water or dirt would be absorbed in the sponge filter before entering the air box? It seems like that would provide more air than that small hole you have?

That would work too.

I avoid filtered air box openings simply because you need to clean them and the filter, I'd rather only have to clean one filter. The biggest down fall to having a opening, filtered or not at the air box door is it's kinda low and easier to get water in the air box which might be fine for your where riding but isn't good enough for the wet trails I ride on. For as filthy as my bike gets I've never had any water get to the air filter, it just gets dusty.

If you want a filtered opening on the air box door check out these...

http://i.ebayimg.com/00/s/NDgwWDg1Mw==/z/C1wAAOSwWKtUruC3/$_35.JPG

Frogzkin They use it on snowmobiles to keep water out of the engine bay. It passes air just fine, but won't pass water. They make generic round, square and rectangular pieces for custom installs. I use a 3 X 3 square on the upper part of my airbox. The piece is 3 1/2 X 3 1/2 and the outer edge is self adhesive. If you buy the 3 X 3 piece, you get two in a package. You can also put it on more places on your airbox, but I just did the top on mine, as a 3 X 3 is large enough for the amount of CFM this bike will eat. It makes a little more airbox noise, but any airbox mods do the same thing.

Traveller wrote:

Frogzkin   They use it on snowmobiles to keep water out of the engine bay.   It passes air just fine, but won't pass water.  They make generic round, square and rectangular pieces for custom installs.   I use a 3 X 3 square on the upper part of my airbox.   The piece is 3 1/2 X 3 1/2 and the outer edge is self adhesive.   If you buy the 3 X 3 piece, you get two in a package.   You can also put it on more places on your airbox, but I just did the top on mine, as a 3 X 3 is large enough for the amount of CFM this bike will eat.  It makes a little more airbox noise, but any airbox mods do the same thing.  

Do you have an info link on this? It only says it keeps out dirt, debris and snow. Doesn't mention water. Have you tried pouring water over it to see if it will not pass water?

The material it's made out of is hydrophobic. It rejects snow and water while still allowing airflow, which is why they use it on snowmobile vents. I've seen several people use it on offroad bikes to keep water out, and allow air to pass. It's the type of material and the way that it's woven that allows it to work like it does. Water will bead on it if you drip it on. It's not waterproof, but it rejects water droplets quite well. They make no claims that you can submerge it however. It's been tested to -40F, so holds up to cold just fine. It doesn't flow as much air as an open hole would, but it lets a lot more air in than a solid piece of plastic would. :) The snow machine guys use it a lot as it keeps water, ice and snow out of the inside of their sleds while still allowing cooling and inlet air in.

Traveller wrote:

The material it's made out of is hydrophobic.   It rejects snow and water while still allowing airflow, which is why they use it on snowmobile vents.   I've seen several people use it on offroad bikes to keep water out, and allow air to pass.   It's the type of material and the way that it's woven that allows it to work like it does.  Water will bead on it if you drip it on.   It's not waterproof, but it rejects water droplets quite well.  They make no claims that you can submerge it however.   It's been tested to -40F, so holds up to cold just fine.   It doesn't flow as much air as an open hole would, but it lets a lot more air in than a solid piece of plastic would. :)   The snow machine guys use it a lot as it keeps water, ice and snow out of the inside of their sleds while still allowing cooling and inlet air in.  

Thanks for the info!