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The KB Performance Piston Kit, model KB297.040, is engineered for high-performance Harley Big Twin engines with a 4.250-inch stroke. Crafted from high-strength, T-5 heat-treated 390 hypereutectic aluminum alloy, these pistons deliver exceptional durability and optimal thermal conductivity. The precision diamond-machined pistons are held to strict tolerances of less than half a thousandth inch and are balanced to within one gram, ensuring smooth operation and reliable performance.
Each kit includes two pistons, pins, spiral-lock pin clips, and Hastings moly rings, providing a complete assembly for rebuild or upgrade projects. The design allows for a tighter fit than conventional pistons, reducing piston rock and enhancing ring seal, which contributes to improved compression and engine efficiency. Replacement rings and pin lock rings are available separately for maintenance or customization.
Due to the unique thermal properties and design of KB pistons, special attention must be paid to the top ring end gap during installation. Proper ring installation is critical to prevent issues such as ring butt seating or failure. Refer to the included instructions for correct piston clearance and ring gap specifications to ensure optimal performance and longevity of your engine.
This piston kit is ideal for performance enthusiasts seeking reliable, high-quality components that maximize power output and engine longevity. Whether rebuilding or upgrading, the KB Performance Piston Kit provides the precision engineering and durable materials necessary for demanding Harley Big Twin applications.
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