
PISTON
The doom shaped piston head is changed to concave shape by grinding so as to make complete utilization of the force exerted by compressed air. The piston rings were removed to aid for the free movement of the piston inside the cylinder.
REPLACEMENT OF SPARK PLUG WITH SOLENOID
The spark plug of the existing engine is replaced with a solenoid (12 V DC, 2 WAY, normally closed).The solenoid is connected to the cylinder head by means of union joints.
The solenoid is connected to the source of compressed air through another union joint making use of copper tubes whose ends are flared. Flaring is done for obtaining a leak proof connection.
EXHAUST PORT

Two ports of 8 mm diameter each have been drilled with a separation of 10 mm center to center distance at a distance of 5 mm from the cylinder head This has been provided so as to transmit the pressure force to the piston and to remove the used air completely to prevent its unnecessary compression when the piston returns to TDC.
Removal of crank case air seal
This has been done for the free movement of crank shaft through the bearings.
Removal of engine fins
To facilitate the proper seating of solenoid valve the fins on the cylinder head were removed. This is possible because the heat generated during the engine operation is negligible which requires no further cooling.