Valve is a series of flaps designed to open and close under
different operating conditions. at low rpm, the valve is closed cos
there is no demand for power
when a certain high rpm is reached, the valve will open, allowing
more petrol and air into the combustion chamber, making for faster
combustion rates and more power.(thus the higher petrol
consumption)
For Honda NSR150SP and similar series, the valves consist of 2
stages. 1st stage open at ard 2-3000 rpm but this is usually not
felt due to the small increase in power required for moving off.
the flaps lift only a small amount
2nd stage open at ard 6.5-7000 rpm. the flaps lift a considerable
amount and opens to maximum lift at abt 8-10,000 rpm. during this
stage of valve operation , you will feel a sudden surge of
acceleration all the way up to 10,500 rpm when the peak horsepower
of the engine is reached.(watch out for 2T levels if intend to stay
in this stage for some time)
contrary to popular belief, changing to high performance reed
valves(eg. boyesen, carbontech, etc) does not really increase
horsepower, it more of affects throttle response and gives a more
accurate feel of the point of valve lift so tat rider can have good
control over the power delivery of the engine.
