What is the effect of shortening or lengthening the Piston?
THE Piston on the VeloSoleX S 3800 is already quite a lightweight affair and there is little real advantage to be gained in shortening the piston by removing some of the Piston Skirt. In fact doing so will increase the “rocking” (or “piston slap”) and general wear within the cylinder. A shorter piston also requires a smaller gap between piston and cylinder to reduce this effect. Too short a Con-Rod also increases cylinder wear. The reason for reducing the weight of the Piston or Con-Rod is to try to relieve the crank of as much inertial load as possible, thus giving increased Acceleration (lighter components) but this does NOT necessarily mean increased Top Speed. If your engine has the Long Piston shown below (49.45 mm long [measured at the edge] for cylinders made before March 1986 such as the TUM 80 [V1], TUM 80A [V2] or TUM 80A CM 6,5 [V3]), a slight increase in Torque (but not top speed) can be obtained by filing some metal from the Piston Skirt nearest the Inlet Port in the shape
