1 SET KB107.040/1 SET 4000AM8.040

This piston kit is offered in Cast Hypereutectic 390 alloy and Forged 4032 low expansion alloy. Hypereutectic 390 alloy contains 16% silicon, providing superior wear and thermal properties suitable for air-cooled engines and street bikes with stock or mild compression (up to 10.5:1) on pump fuel. Forged 4032 alloy, with 11% silicon, offers better resistance to cracking under detonation, making it suitable for street or race applications with power adders. Kits include pistons, Hastings rings, pins, and spiral locks. Pistons feature fully machined valve pockets with ultra-flat ring grooves and are weight-matched to +/- 2 grams.