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: 686cc. Bore - Standard: 78.00mm. Bore - Actual: 79.00mm. Bore - Oversize: 1.00mm. Stroke: 70.00mm. Cylinders: 2. Engine Type: 670 HO. Note: Pro-Lite. Note . Values