Description
Spears Racing 678cc + 2mm overbore Pistons SV650 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. These pistons also have had the domes (tops) of each unit brushed ,this will insure that all of the sharp edges of the dome and not creating more heat in the combustion chamber.
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.
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.
The 2mm overbore Pistons SV650 compression is 12.5 to 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.
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.
CP GROOVE CP Groove stands for Constant Pressure Groove. This groove is a channel on the lower part of the top land and equalizes pressure to the top ring groove. When used in combination with lateral gas ports, the CP groove helps keep gas ports clear of carbon build up. In addition, the CP groove prevents the top land from smearing into the top ring if the land rubs the cylinder bore.
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.
Cam and Barrel Extensive research and development has been done to find the optimum skirt shape for each piston. Having the correct cam and barrel on a part promotes the following:
1. Tighter clearances
2. Less noise
3. Better ring seal
4. More power
5. Durability
CUSTOM LASER LOGO/SERIALIZATION Each Spears Racing Piston is custom laser marking with the Part number, Job Batch and the Spears Racing Logo.
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:
Pistons x 2
Wrist Pins x 2
Piston Rings x 2
Cir Clips x 4
2007/2018 you will need to Bore and re-plate your cylinders on these years, chrome plating from the factory.
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