4 Valve Cylinder Head

KOSO 4 Valve Cylinder Head — High-Flow Performance Upgrade

Upgrade your Koso 170cc Big Bore kit with the KOSO 4 Valve Cylinder Head. Engineered for increased airflow and combustion efficiency, this 4-valve design delivers noticeable gains in both power and torque for Honda Grom® applications fitted with the Koso big bore kit.

Key Features

• High-flow 4-valve layout for improved intake and exhaust efficiency
• Forged piston included for enhanced strength and durability
• Stainless steel valves: 24 mm intake and 20 mm exhaust for reliable performance
• Specifically designed to fit the Koso 170cc Big Bore kit
• Optimized combustion chamber for increased torque and throttle response

Important Notes

Legal: Not legal for use in California on pollution-controlled vehicles; race use only in California — waiver available.

Installation: Requires the use of an iridium spark plug. Professional installation recommended to ensure correct tuning and fitment with the Koso 170cc kit.

Ideal for riders seeking a reliable performance upgrade for track or off-road competition, the KOSO 4 Valve Cylinder Head pairs seamlessly with Koso big bore components to unlock the engine’s potential.