Yamaha R3 Overbore +2mm Piston Rings 339.43cc


Piston Rings form the critical seal between the piston and the cylinder wall.


Piston Info

SKU: SP12-320 Piston Rings Categories: , ,


339.43cc/2mm over piston rings: Piston Rings form the critical seal between the piston and the cylinder wall. A delicate balance exists between proper sealing for maximum power and minimum blow by, and the correct amount of pressure on the cylinder wall to minimize drag which can lead to power loss and excess wear. Additionally the rings help to carry oil up and down the cylinder wall. Fresh rings are a key component when building a high performance engine. We offer a selection of rings for every piston style and diameter. If you are unsure what rings you require for your stock or overbore pistons, please contact us before ordering.

Yamaha R3 2mm Piston Rings
For 70.00mm Spears Racing +2mm
A direct replacement for the Spears Racing Piston Design (two ring design)
Top Ring 0.031″ / 0.8mm THICK
Top Ring is a Chrome Faced Stainless Compression Ring
The Oil Ring Assembled is a 0.059″ / 1.50mm Thick three piece low tension ring set


Spears Racing Piston Specs:

Spears Racing’s Yamaha R3 2mm Piston Kit this is the new 2 Ring FSR Slipper Skirt forging Piston. This kit includes pistons, rings, lighter wrist pins, cir clips . The compression is 13 to 1. Dome features smooth flowing radius, under crown machining to lessen the overall weight. Anti Det. Grooves, Acc Grooves, Double Broach Grooves for extreme applications including professional competition.

Spears Racing  has been designing and making race pistons with the State of the Art CNC Machining and manufacturing alliances with CP Carrillo 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.This Yamaha R3 2mm Piston kit will add more torque and RWHP. This design is lighter than OEM and comes with 1mm o/s valve pockets and deeper pockets to allow the Spears Racing Camshafts to fit with this new design.

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.


Yamaha R3 2mm Piston kit Includes the Following:

Pistons x 2

Wrist Pins x 2

Yamaha R3 2mm Piston Rings x 2

Cir Clips x 4

Detailed install specification sheet.