Modern race bikes use four stroke engines for racing. Two stroke engines are not used because they cause large amount of pollution due to incomplete combustion & incomplete exhaust. If these two problems are overcome then two stroke engine will be a better option for race bikes.
The modified components are exhaust Manifold, twin spark plugs & a heat exchanger is introduced to heat fresh charge for more complete combustion. The material for the heat exchanger is chosen such that it will not heat charge up to its flash point, it will heat charge up to a limit such that problems related to SI engines like detonation, pre ignition will be avoided.
The working of new model is as follows-
1. When the piston is at top dead centre (TDC) the fresh heated charge will be introduced into crankcase.
2. As the piston comes down to bottom dead centre (BDC) the heated charge will go up in combustion chamber. In the next stroke the piston will compress this fresh charge and the charge will be ignited just before the end of compression stroke. The twin spark plugs will help to burn maximum charge and compensate for incomplete combustion. Also twin spark plugs will provide increased thrust on the piston delivering maximum power. The piston will be pushed to BDC due to expansion.
3. The exhaust valve will be opened just before the end of expansion stroke, and exhaust gases formed will rush through exhaust valve, as the gases reach the convergent portion of the exhaust manifold partial vacuum will be created and this will help to draw more gases from combustion chamber. Thus modified exhaust manifold will help to get maximum scavenging.
4. The exhaust gases will now be supplied to the heat ex changer. In the heat exchanger the heat of gases will be utilized to heat incoming charge. The material for the heat exchanger is chosen such that it will not heat charge up to its flash point, it will heat charge up to a limit such that problems related to SI engines like detonation, pre ignition will be avoided.
5. The use of heated charge will help in complete combustion of gases and thus the emissions from the two stroke engine will be reduced.
After these modifications two stroke engine will be a better option for race bikes.