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40mm 60CC Big Bore Cylinder Kit For Yamaha PW50 PY50 QT50 MA50 1981-2026
Aftermarket big-bore upgrade kit, NOT a genuine Yamaha OEM component. It upgrades 50cc models to 60cc, replacing specified OE numbers, and boosts performance for Yamaha small-displacement motorcycles.
Cylinder/Piston Bore Diameter: 40mm (big-bore upgrade from stock 39mm). Engine Displacement: 60CC (upgraded from 50CC). Replaces OEM Part Numbers: 4J2-11311-01-00, 18U-11631-00-A0. Package Components: Cast iron cylinder block, piston, piston rings, piston pin, circlips, full gasket kit.
Construction: High-strength cast iron cylinder, durable aluminum alloy piston, premium sealing piston rings. Big-bore upgrade increases displacement to 60cc, improving low-end torque and power output for youth riders. Direct drop-in installation, perfectly matches Yamaha OEM dimensions without modification. Heat and wear resistant for long-lasting durability in light terrain and daily riding scenarios.Built to withstand the demands of small-displacement and youth motorcycle use. Independent aftermarket product, has no affiliation with the Yamaha brand. 1 × Full 40mm 60CC Big Bore Cylinder Piston Ring Kit (all components needed for engine top-end overhaul/upgrade).