Forged aluminum piston set for stock stroke and cylinders. 9.2:1 CR with 69cc; 10.1:1 CR with 62cc; 11:1 CR with 55cc and 11.6:1 CR with 51cc cylinder heads. Piston weight 360 gr. / Piston pin 97gr. Head type: Domed with -1cc. Compression height 1.210". Bore 3.498" / Stroke 3.812" / Rod length 6.926". Comes with T6 heat treated 390 Hypereutectic cast pistons with 16% silicone levels which enables running a very tight clearance for longevity and hardly any piston noise. Note: All KB forged pistons come equipped with offset wrist pins / piston pins. There is a front and rear section on the piston and it is necessary to install it in the correct way. Please refer to the installation instructions; as provided with each piston set; prior to installation.