This complete big bore top-end cylinder kit is designed for Honda 286cc engines, including CBR300R (2015-2016), CRF300L (2021+), CRF300 Rally, CB300F/R, CMX300 Rebel, and CRF250L (with conversion) . The OEM standard bore is 76.00mm — this 76mm kit maintains standard displacement. Precision dimensions: piston diameter 76.00mm (standard bore), piston rings 76mm set (2 compression rings + 1 oil ring), piston pin 15mm. The kit includes: 76mm cylinder block (aluminum alloy), 76mm piston (flat top/dish type, 10.7:1 stock compression), piston rings, wrist pin, circlips, and full top-end gasket set (cylinder head gasket, base gasket). For performance upgrades, 76.25mm (+0.25 oversize) high compression dome pistons (12.3:1 CR) and 78-79mm big bore kits (305cc) are available. Compatible Models: Honda CBR300R (2015-2016), CRF300L (2021+), CB300F/R, CMX300 Rebel, CRF300 Rally. Professional installation recommended for complete top-end rebuild — proper ring gap and torque specs required. Ideal for restoring lost compression, eliminating blow-by, reducing oil consumption, and performing complete top-end maintenance on 286cc single-cylinder engines. Perfect for sport riding, off-road adventure, and engine rebuilding.