RedCap 50mm conversion to 100cc Big Bore Kit Cylinder & 69mm Head Assembly, designed to convert standard 50cc engines to a higher performance capacity close to 100cc. Engineered for 139QMA and 139QMB GY6 engines, this big-bore kit delivers improved acceleration, stronger torque, and smoother throttle response. It is an ideal performance upgrade for riders looking to enhance the capability of their moped, scooter, ATV, go-kart, or quad bike without replacing the entire engine. The precision-machined cylinder and matching head assembly ensure proper compression and optimized airflow, helping your engine perform more efficiently.

Constructed from high-quality, durable metal alloy, the RedCap big bore cylinder kit is designed to withstand higher temperatures and engine stress associated with increased displacement. The robust build quality helps provide long-lasting reliability and consistent engine performance even during demanding riding conditions. Designed as a direct replacement upgrade, the kit fits most Chinese GY6 50cc 4-stroke engines, making installation easier for mechanics and DIY enthusiasts. Whether you are restoring a scooter, upgrading a go-kart engine, or boosting the performance of your ATV, this big-bore kit offers a dependable and practical solution for increased power and improved riding performance.

• Perfect Fit: Designed specifically for GY6 139QMA and 139QMB engines, this 50mm Big Bore Kit provides an excellent fit for 50cc scooters upgraded to approximately 100cc performance. The precisely engineered cylinder and head assembly ensures proper alignment with engine components, helping maintain stable operation and smooth performance for your moped, scooter, ATV, or go-kart.
• Wide Compatibility: This big bore cylinder kit is compatible with a wide range of Chinese scooters and small engine vehicles including mopeds, ATVs, go-karts, quad bikes, and mini scooters equipped with GY6 50cc 4-stroke engines. It works with most 139QMA and 139QMB engine models commonly found in brands like TaoTao, Roketa, Sunl, and other similar platforms.
• Enhance Performance: Upgrading to a 50mm big bore kit increases engine displacement from the stock 50cc to nearly 100cc, delivering improved acceleration, stronger torque, and better overall engine response. This performance upgrade helps your scooter or ATV achieve smoother power delivery and more efficient riding, especially when carrying heavier loads or climbing hills.
• Durable Construction: Manufactured from high-quality metal alloy materials, the cylinder and head assembly is built to handle higher temperatures and increased engine stress created by a big bore upgrade. The robust construction helps improve engine reliability, supports longer service life, and ensures dependable performance during daily rides or demanding driving conditions.
• Easy Installation: Designed as a direct replacement upgrade kit, this big bore cylinder and head assembly can be installed using standard tools with minimal modification required. The precision-machined components help ensure proper sealing and alignment, making it suitable for both experienced mechanics and DIY enthusiasts looking to upgrade their GY6 engine.

Know to Fit:

• GY6 50cc to 100cc 139QMA 139QMB Engine For Moped Scooter ATV Go Kart Quad