ok this is the hard part..
i m seriously not sure myself, BUT then this is wad i think, the
valve controls your fuel intake, the reason why it open in the
beginning is for your pick up, it closes in the mid range coz u dun
need that much power n this is the part where u will be most of the
time, in this way it help u save petrol also, then for high rev, it
gives u the power u need, if not, then u wont be in high
rev....
pls pls,. correct mi if i m wrong