Vertex 125 Piston Kit - Sherco 125 2000>2013, GasGas 125 1997-2001+Edition

Piston Sizes

The factory recommended piston to cylinder tolerance for the 125 is listed as 0.0175 to 0.0225 mm in the early 2003 to 2009 manual (we aim for a more realistic 0.03mm), Sherco have now changed this to 0.02 to 0.03mm in the 2010 to 2013 manuals, if you are considering putting the next size up piston in please be aware that your original piston will have worn down and any wear in the cylinder is unlikely to be uniform down the bore so please check the bore size all the way down the cylinder and from left to right as well as front to back, the factory measure the piston and cylinders at 24 degrees C. The piston is measured front to back and 19mm up from the bottom of the skirt, be aware that the pistons are manufacture tapered (larger at the bottom) and oval (larger front to back) to allow for unequal expansion of the piston in use.