This situation is usually caused by continuous injection of fuel by a certain cylinder injector of Bare Engine. Often before that, there will be difficulties in starting, idling jitter, black smoke from the exhaust pipe, and power reduction.

After disassembly and inspection, it can be judged by observing the combustion of each cylinder.

Since the combustible mixture is richer than other cylinders, the cylinder and cylinder head will be darker than other cylinders. At the same time, the injector and its injection control circuit can be further checked.

Bare Engine are bent or broken due to locking of connecting rods and crankshafts.

This situation is usually caused by poor lubrication of Bare Engine, which can be judged by checking the wear of internal parts of Bare Engine.