Attributes . Forged from high-silicon aluminum alloy for maximum strength and dependability.. Innovative forging design and piston skirt provide maximum horsepower and torque.. Wiseco High-Performance piston kits are priced with piston, rings, pins and circlips (unless noted otherwise).. Oversize pistons require cylinder sleeving.. SPECIFICATIONS. Displacement: 178cc. Bore - Standard: 64.50mm. Bore - Actual: 65.00mm. Bore - Oversize: 0.50mm. Stroke . Values