why we use a airbox ............................

[ThAzKat]

This is the best explanation I have found as to why we/katana riders should use a airbox and/or any bike that falls under this:
Airbox
When running a full body and fairing combination on your drag bike it is essential that you install an air box. The air is streamlined around your fairing causing a dead air space in the area of your carburetors. This starves your carbs of air and performance is dramatically decreased as much as three tenths or more. Lining your airbox with a heat reflecting material will keep engine heat out so that you have clean cool air.

http://www.aperaceparts.com/COPE.HTML I want to thank ape racing for this info!

On their site is alot of great information and why we do the performance upgrades.

[arsenic]

APE sorta know what they're talking about

[Tmod]

I would like to throw something out there as well, When you run the carb vent hoses make sure they are as close to the air inlet as possible that way the float bowl will feel the same pressure as the intake side of the carbs. I know a snowmobile is not the same but I had problems with the carbs going rich at speed and once I connected the float bowl vents to the airbox the carbs sensed the same pressure and would no longer vary in calibration.

Tmod

[Kfreak]

If you connected the vent tubes to the air box on a snowmobile carb isn't that going to create a vacuum on the vent tube?

[Tmod]

It will create the same feeling that you get on the intake side of the carbs, In other words it would equalize pressure between the two.

Let's use a example here. Say for instance we were running the engine on the dyno where we are not moving so there is no pressure variance. Now when installed in the frame and running down the road or snow we have a pressure area where the carbs are at. It takes very little pressure variance to creat either a lean or rich condition as the float bowl and fuel deliverd is very sensitive to changes in pressure. So if it was a negative pressure on the float bowl you would run leaner and a postive pressure would make it richer.

IMO that plays a part in why a dyno tune will not always provide a spot on calibration, As you are not moving and taking into account other effects that the engine will feel.

Tmod

[kevin2502000]

Airbox
When running a full body and fairing combination on your drag bike it is essential that you install an air box. The air is streamlined around your fairing causing a dead air space in the area of your carburetors.


I also came across a similar site which showed a airflow chart at different speeds. The 1 and 4 cylinder get the full force of wind creating a slight pressurized effect, the 2&3 just the opposite, it actually creates a slight vacuum pulling the airflow out towards the sides of the bike. That is why the 2 & 3 will run more rich than 1 & 4. This model was any 4 cylinder inline but the specific bike was the 1100.

[Kfreak]

Understood on the balance.

[ThAzKat]

that is very helpful to explain the balance bro, thank you so much!