Racing cylinder 125-180 ccm, stroke 53-56 mm for Vespa 50-125/PV/ET3/PK/XL/Ape by SIP Scootershop
54 mm stroke is currently the magic word in smallframe tuning. With a crankshaft with 54 mm stroke, you have a significant increase in displacement and, as already said, "more displacement = more power". All cylinders of the 125 cc class 51 mm can also be run with a 54 mm shaft, but must be fitted with suitable head and base gaskets. The following cylinders are only designed for 54 mm or 56 mm shafts.
Customers ask - SIP answers
"What is the point of setting cylinders higher or lower?"
By "raising" and "lowering" cylinders, you can specifically influence the overflow and exhaust timing of an engine - the special focus here is on the overflow timing. The usual way is to raise the cylinder by means of a metal foot gasket in order to lengthen the timing and make the engine more rev-happy and powerful. However, the foot gasket also changes the position of the top of the cylinder as well as the compression of the engine, which usually requires further work on the cylinder and/or cylinder head. Reworking the exhaust is also almost always necessary or desirable.
