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For ZS NC250 84mm Big Bore Cylinder Piston Gasket Kit 300cc
This complete big bore top-end cylinder kit is designed for Zongshen NC250 (ZS177MM) engines, upgrading displacement from 250cc to 300cc using an 84mm cylinder and piston assembly. Engine specifications: 84.0 mm bore × 53.6 mm stroke, 297-300 cc displacement (upgraded from OEM 77mm/250cc). Precision dimensions: piston diameter 84.0mm (big bore from OEM 77mm), piston rings 84mm set (2 compression rings + 1 oil ring), piston pin 16mm (50mm length). The kit includes: 84mm cylinder block (aluminum alloy), 84mm piston (forged/cast options), piston rings, 16mm wrist pin, circlips, and full top-end gasket kit (cylinder head gasket, base gasket). Aftermarket versions include forged pistons with Nikasil-coated cylinders from OTOM (82mm/84mm options). This is a big bore performance upgrade - not OEM standard size (77mm). Professional installation recommended for complete top-end rebuild - proper piston ring gap and torque specs required. Ideal for NC250 300cc conversion, restoring lost compression, eliminating blow-by, and refreshing top-end performance. Perfect for KAYO, BSE, KEWS off-road racing, motocross, and engine performance upgrades.