Analysis of Causes of Insufficient Cylinder Pressure

Cylinder pressure refers to the size of the cylinder compression force when the piston reaches the top dead center at the end of compression. Insufficient cylinder pressure means that the cylinder seal is reduced, which will reduce the engine power and make it difficult to start. If the individual cylinder pressure is insufficient, the engine will run unstable.
cause of issue
1) The side clearance and open end clearance of the piston ring are too large, or the labyrinth route of the gas ring opening is shortened, or the sealing of the piston ring; after the surface is worn, its sealing performance becomes poor.

2) Excessive wear between the piston and the cylinder will increase the gap between the matching cylinder and the piston will swing in the cylinder, which will affect the good sealing of the piston ring and the cylinder.
3) Because the piston ring is stuck in the piston ring groove due to glue and carbon deposits, the elasticity of the ring itself cannot be exerted, and the first sealing surface between the gas ring and the cylinder wall is lost.
4) Mismatched piston is installed. For some engines, the depth of the pit on the top of the piston is different, and the wrong use will affect the cylinder pressure.
5) The cylinder gasket is damaged, the valve-seat ring is loose, the valve spring is broken or the spring is insufficient, the valve and the valve guide are not tightly sealed due to carbon deposits or too small clearance, which hinders the up and down movement of the valve, etc.
6) The timing gear is installed incorrectly, the gear keyway is incorrect, the timing gear is damaged or worn too much, the wheel load on the camshaft timing gear and the wheel are loose, etc., resulting in incorrect gas distribution phase.
7) Unmatched cylinder heads are used. If there are cylinder heads, the combustion chamber volume may be different. If installed incorrectly, the cylinder pressure will be affected.