Yamaha R3 Overbore +2 mm Piston Kit/Cylinder/Gaskets 339.43cc

Description

Spears Racing Overbore 339.43cc Piston Kit  have been designing and making race pistons with the State of the Art CNC Machining and manufacturing alliances with JE Pistons for decades. Spears Racing continuous committed to excellence to advance as the industry changes. This commitment has resulted in more forgings specific to certain applications, proprietary treated wrist pins and piston rings manufactured only for us. Each of these aspects has been put through stringent research and development stages to ensure that our product will exceed your standards.

At the forefront of performance, piston manufacturing has been a result of continuous research and development both in the dyno room and on the race track winning championships all over the world.

They stock OEM cylinder is bored and the cylinder is inspected and coated with a  proprietary Nickel Silicon Carbide (NSC) cylinder plating process and cylinder services. This NSC process is so superior to factory plating that Millennium Technologies is often used by professional race teams all over the world to re-plate brand new OEM cylinders. Millennium stands behind our plating with a LIMITED LIFETIME WARRANTY.

Overbore 339.43cc Piston Kit: This is the new 3 Ring FSR Slipper Skirt forging Piston made for Spears Racing  by JE Pistons. This 2mm over kit includes pistons, rings, lighter wrist pins, cir clips . The compression is 13.5: 1. At the forefront of performance, piston manufacturing has been a result of continuous research and development of unique materials, piston designs and technologies. Utilizing State of the Art CNC machines for manufacturing, along with purpose-designed forgings, while being able to maintain exacting specifications on each and every piston – holding tolerances to millionths of an inch. This is the new forging that is lighter than stock OEM Pistons.

Each Kit comes with a OEM Yamaha base and custom plus 2mm over  head Gasket to a special thickness . Spears Racing’s designs are specifically engineered for extreme applications including professional competition. Comp Ratio 13.5:1.This is a 3 ring design piston

Piston Terminology for Spears Racing Pistons:

ANTI DETONATION GROOVES (CONTACT REDUCTION GROOVES) Also know as contact reduction grooves, which limit the piston/cylinder contact during high temperature and high RPM. These grooves also protect the top ring by disrupting detonation waves

ACCUMULATOR GROOVE V-shaped groove machined in the 2nd ring land that adds to the volume between the top and second ring. This groove accumulates residual gasses from combustion which alleviates top ring flutter and premature second ring wear, improving ring seal.

DOUBLE PIN OILERS Double Pin Oilers (opposed to single pin oilers), in conjunction with our annular reservoir, can add twice the amount of oil from the cylinder wall to the wristpin bore. This is a standard option on any piston that receives forced pin oiling.

PIN FITTING The pin bore is precision honed to attain an exact pin clearance. Depending on the application clearances typically range from .0003 to as much as .003 between the wristpin and bore.

Spears Racing Piston Kits have been winning races and Championships all over the world for over 4 decades. Spears Racing pistons have been in several of the race wins in close course racing and in road circuits in Europe and has won the Isle Of Man TT Twins  several times.

“Preferred Performance” Pistons Kits By Spears Racing

Kit Includes the Following:

New Bored Re-Plated cylinder

Pistons x 2

Wrist Pins x 2

Piston Rings x 2

Cir Clips x 4

Custom 2mm over head gasket

Spears Racing Overbore 339.43cc Piston Kit Complete This is a complete engine kit, +2mm over bore High Compression piston kit (339.43cc).