YFZ450 Application: Increases engine compression ratio to 13.0:1 (stock '06-'09 is 11.2:1 and '04-'05 is 11.9:1). Offers 1.5 to 3 hp increase throughout most of the power band. No crank rebalancing necessary. Piston is forged aluminum with machined valve pockets for additional valve clearance when higher lift camshafts are used. Includes piston rings, piston pin and clips (uses stock replacements). GYTR top end gasket kit (GYT-5TG04-10-00) required for installation. Requires use of minimum 100 octane racing fuel. YFZ450R Application: Increase engine compression ratio to 13.2:1 (stock is 11.4:1). Offers 1.5 to 3 hp increase throughout most of the power band. No crankshaft rebalancing necessary. Piston is forged aluminum with machined valve pockets for additional valve clearance when higher lift camshafts are used. Includes piston rings, piston pin and clips (uses stock replacements). Uses stock gaskets (not included). Requires use of a minimum 100 octane racing fuel. This accessory may be restricted to closed course use. This performance accessory does not meet California standards for off-road recreational vehicle usage regardless of model year.
