ProX Piston Kit YZ400F 98-99/WR400F 98-00 12.5:1 (91.97mm) ProX pistons are precision machined on the latest, state of the art CNC equipment. The same low-expansion, low-friction piston alloy is used as is used for all major Japanese engine manufacturers. ProX Piston Kits are a first class solution to replace the original piston in your Motorcycle, Scooter, Moped, ATV, Personal Watercraft, etc. Coated for ultimate performance
Most of the ProX pistons come with a coating. Our OEM style Tin coated pistons assist the wear in process when you just started the bike.
We have developed a new skirt coating that not only assists the wear in process, but also helps reducing friction after the wear in. The black coating is made from a delicate mix of materials and will increase performance. ProX pistons for Nicasil/plated cylinders
The latest cylinders are plated by a Nicasil plating. Therefore we offer a wide range of ProX pistons in standard size, as well as in A, B, C, D+ oversizes. ProX pistons for sleeved cylinders
ProX Piston Kits for sleeved cylinders are available in standard size and a wide range of oversizes. The availability of oversizes up to 2mm significantly helps to increase the lifespan of a cylinder by offering more re-boring possibilities.
Take advantage of the additional oversizes to extend the lifespan of plated cylinders. All ProX Piston Kits are supplied complete with Piston Rings, Wrist Pin and Circlips, ready to install! Piston Kit Includes Piston Ring set Gudgeon Pin  Circlips