Because much smaller than the exhaust air flow velocity, in order to reduce intake resistance and improve gas flow, to increase engine power!
Some of the engine intake lift not only large, more than the intake valve (eg, five-valve, into the 3 row 2), valve diameter, but also large!
some of the gases are burnt and reduced befor going to the exhaust
The intake valve is always bigger than the exhaust valve because there is more volume going in to the cylinder than coming out.
because the inlet valve has to hold back pressure from the gas pump where as the exhaust valve has nothing to hold back but the compression of the ignited fuel and such a force is applied at the face of the valve. the face of the valve is in the cylinder so the force is a push not a pull meaning a bigger exhaust valve is not needed because the valve dose not have to fight back to keep it's self closed.
An inlet and exhaust valves are two separate things. The inlet valve lets the fuel/ air ,ix into the cylinder. The exhaust valve opens to let the pressure out after the mix has burned, releasing the gasses. Then the process starts over again.
the difference is that the inlet valve takes air (oxygen) from surrounding in order to combution of fuel which result in blast by air fuel mixture and piston rotates while the exhaust gases removed from the exhaust valve.again the inlet valve opens first before blast and exhaust valve opens afterward
metal (steel)
it was invented by a man called Justin Andrews . valva lag- inlet valve closes after B.D.C -exhaust valve closes after T.D.C
With No1 cylinder at TDC adjust the following valve clearances, No. 1, inlet and exhaust No. 2, inlet No. 3, exhaust No. 4, inlet No. 5, exhaust Then turn the crankshaft 1 full turn so that No 6 cylinder is at TDC and adjust the following valve clearances, No2. , exhaust No. 3, inlet No. 4, exhaust No. 5, inlet No. 6 inlet and exhaust. Both inlet and exhaust clearances ar 0.4 mm with engine cold. This info is from the original service manual
Three. Inlet valve, fuel injection valve, exhaust valve.
Hi, inlet is 25mm and exhaust is 22mm
intake valve is bigger.
Inlet .2 Exhaust .4