Air Box Mods

[Tigger]

Has anyone removed the airbox or the airbox cap and successfully jetted it?

[tlr2nv]

Has anyone removed the airbox or the airbox cap and successfully jetted it?

I reckon there's gains to be had with some kind of airbox mod, but everyone keeps saying to leave it alone.

[motopix]

don't bother. better still, don't do it. at most, remove the filter in there but keep the airbox.

it's been discussed many a time.

[boinovRS]

Ive changed the airfilter with very thinest one(made in by me).There is MORE acceleretion!

[Smoke Eater]

I wouldn't remove the filter unless this is a dedicated race bike that you plan to rebuild all the time. The AF1 filter is so thin that I really can't see it restricting much air. I even oiled mine because it looked too light.

[keean]

The problem with changing the airbox, as far as I understand it, is that changing the airflow changes the carburation. To be more precise the carbs rely on negative pressure to draw the fuel into the airflow. The restriction in the airbox (the tubes through which air comes in) increases the negative pressure in the carbs... When you remove the restriction (say by removing the airbox lid) there is less negative pressure, less fuel will be drawn in, and the engine will run lean. You can compensate for this be fitting larger jets (search for jetting), however without the extra negative pressure from the restriction the carbs will become a lot more sensitive to weather conditions (temperature and pressure). Because of this you have to balance how often you wish to rejet against how much you wish to remove the restriction. If you just want to forget about jetting and ride, you probably should leave the airbox alone. If you are prepared to check the jetting before each time you ride (say for a track bike) then could remove the airbox lid. If you want to have very unstable jetting then you could remove the airbox and replace with K&N style filters (has anyone got a setup with K&N filters running reliably?).

[Hankster]

AF1 Racing checked the power gain on a dyno and reported in an earlier thread there was only a 1 to 1 1/2 HP gain by removing the airbox. They also determined the motor uses a significantly greater amount of fuel with the bigger jetting. Keep the airbox, use a thinner head gasket ( 0.030 in. ), and advance the ignition timing ( 3 to 5 degrees ). Cheap and reliable upgrade for premium unleaded pump fuel ( 93 pump octane R+M/2 ).