What is the best mods that I can do to a stock air box on a V700?

 

Air, Air, Air, the big V likes a lot of air. Some stuff to ponder it is almost impossible to attain a positive pressure in the air box a positive 1 would be fantastic but not possible. At 50 mph you will if the air box is a tunnel ram system get 0.35 pressure. At 80 mph you may acheive 0.48 pressure. At 150 mph you may be lucky to have around 0.75 atmospheres of pressure in your air box. It is better to have cool air but cool air and warm works well too. You can go expensive with DG's snorkle to gain more air from the front but it is just as easy to install flexable vacume hose from HomeDepot for a fraction of the price.

Basicly drill 2 holes 1/2 inch in size one above the other at a 1 1/2 centres where the bottom one is 1 inch above the bottom of the air box then go sideways 2 inchs from centre repeating the above each other scenario. On the inside of the air box at the front where the snorkle mounts there is a solid wall to stop moisture from entering into the airbox, remove most of the material to allow for straight flow into the box. Drill another hole the size of the flexible vacume hose beside the main intake but to the right of the mane intake hole, position it close to the front of the bike under the handle bars. The plastic in front of the V that is louvered remove the smaller sections of the plastic to allow for free flowing air from the front to pass through the now close air intake hoses you have mounted very near the front end. Along with your K&N filter I will guarantee you will have to rejet your carbs again as opening up the airbox it will lean your system a good deal. If at anytime you think it is getting to much air then tapr over some of the holes. One more thing don't drill any holes in the back of the air box just along both sides. I am currently testing a new type of sponge air filter that flows better than the Twin Air but is as good as the Twin Air for keeping your system clean. K& N is alright in nondusty conditions but Twin Air is better in my opinion. If you have K&N with outer wares then you may as well have your stock filter back in this is my findings using air flow technology. I made up XC800 airbox and front louver system he came up with vacume hose if he is reading this post he may give the part number from HomeDepot for you.

If you have one hole for air to push into the box you will get a vortex situation, swirling motion in the box this detrimentall to any performance as it will take valuable air away from the carbs. If you have an equal amount of air coming in from both sides then the air will flow along both sides of the box meeting at the back of the box then flowing up over the carbs back to the front and to the sides this causes a constant pressure a good thing for performance. This is not good for stream crossings or muddy conditions if you have 2 air boxs you switch when the need arises or just tape off some holes hope this helps.

 

Thanks,Alltoys

 

Check out my pix page for the Air Hose I used. It is in the Central Vacumn section of Home Depot. It fits perfect in the stock intake.

I used a dremmel to cut out the inside baffel plate. Alltoys marked the hole as he outline. I drilled out the holes and ran the bike before I cut out the baffel plate and added the second intake. I thought maybe it will be a tad much air so I duct taped all the 1/2" holes except in the front. Out on the trail during a break, I thought what the Hel! and remove some of the tape. Seemed to make adifference for the Good. I stopped again and removed all the tape. Works even better!! I am currently running 160 /165 jets with the K&N.

I am not in the dust vry much unless I go to Brule so the naked K&N works fine.

 

Vnasty:

I see by your mod list, do the above and then try some heavier levers and the HPD plain. YOu LOVE the difference. But you must do both

 

I like picking on Alltoys j/k, so let me just throw this out there. Suppose you could achieve +0.35 atms of pressure at 50mph (which I think is impossible). 0.35atms = 5.14 psi. Now suppoose the surface area of your lid is about 1 square foot or 144 square inches. Multiply area by pressure and you will see you have 740lbs of internal force that would break you lid clips off.

So the point is, I think the airbox would fail (bust open) at about 0.05 atms. I also dont think you could achieve any measureable positive pressure without a turbo.

But that was kinda off topic becuase we are talking about holes, an I like Alltoys suggestions regarding holes.

 

Why are the small 1/2" holes necessary? This is a good study in airflow theory. Just trying to understand the science of it.

 

Green 700,
Point taken, sitting still at rest 0 atmosphere even if it is sea level or 10,000 foot elevation. Move at a rapid rate atmosphere is still at 0 but the force exerted against the moving object creates pressure and so on. 1/4 mile racers are always trying take advantage of the amount of air introduced to the intake to gain as much power as possible in a naturally aspirated motor. I experimented by putting a clear plastic top on the air box then taping very light paper to the side of the air box at different places. True not very scientific but this allows me to see where the air is going inside the air box. On my old 650 I had holes in the top of the lid as I thought this is the best way to get air inside the box with air filter on top. If you have ever noticed the Keihin carbs throw fuel straight up almost uses to much then sucks it back later to enrich the fuel circuit. Since noting how the 03 style of air filter has a solid top I was going to again put holes on top of the lid. After I played around with clear top and paper on the sides I found the best combination is what I stated earlier the carbs like an enclosed top so the fuel can be sucked back into the carbs. You will always gain a positive pressure once you start moving in the air box the problem is you need volume as there is not enough positive pressure to supply the carbs from a small restricted hole. One more thing you may find interesting, if you use the horns off the 02 put them on the 03 with the new solid top filter you will gain a better fuel mixture especially if you have the box done like mine or XC800.

 

I'm not a engineer, but this is my experience with air.

best scenrio is to get air to move at highest possible rate of speed into the carbs.. To get this, a person needs to figure how much air is needed, have that size hole in the air box.

anything that is a supply line to that hold needs to be larger. tapered so it starts large and gets smaller the closer to the inlet hole to the airbox.

Think about a stream, where it is wide the water runs slow, as the stream narrows the water moves faster, because the same volume is passing as in the wide spot, this is the effect I'm talking about.

Am I right in my thinking.

I have often though that by drilling holes in the air box cover, you might actually be taking away air from the carbs, by having a place for the air to escape. Air will follow the path of least resistance, so it might come in the snorkel, (forced in by your speed) and out the holes.

I understand the carbs are pulling air, but are you losing any pressure effect by holes because it would be easier for the air to go out the holes rather than through the filter.

In xc800 case, was he gaining performance because he was allowing more air in or was he gaining because he had to much and letting some out by removeing more tape.

I know lots of people drill holes, so there something to it.

Alltoys, I know you've got it figured out, what do you think?

 

XC800,I have the Dalton Clutch Kit and Plate on order ,should be here next week.Thanks for the info.[img]i/expressions/face-icon-small-cool.gif[/img]