The cylinder with piston is the core of the piston assembly: the piston moves inside it and compression is created. The size 100.00 in the name refers to the 100 cc displacement of the tuning version. Country of origin: China.
Replacement is needed when compression drops, the bore is scored, oil consumption is high, there is smoke from the muffler, or the engine is hard to start. Choose by the diameter given in the name.
