KOSO Big Bore Kit
Upgrade power and reliability with the KOSO Big Bore Kit — a complete high-performance overhaul designed to increase displacement while maintaining everyday drivability.
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Complete kit: ceramic-coated cylinder, 61mm forged piston, piston rings, wrist pin and clips, full gasket set, and banjo bolts
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High-strength internals: forged 61mm piston for increased durability and consistent performance under load
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Advanced cylinder finish: ceramic coating reduces wear and improves heat management for longer service life
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Optimized compression: 11.5:1 compression ratio allows safe use of premium pump gasoline while preserving stock motor reliability
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Easy install: gasket kit and hardware included for a straightforward rebuild
This kit is ideal for riders seeking a noticeable torque and horsepower increase without sacrificing daily reliability. Perfect for sport scooters and small-displacement motorcycles where smooth power delivery and longevity matter.
