Best 1P39QMB Big Bore Kit Upgrades for GY6 Scooters and Mopeds
Looking to boost power, RPM, and top speed on a GY6 scooter or moped powered by a 1P39QMB engine? This article highlights top big bore kits that upgrade displacement from 50cc/60cc up to 100cc while preserving a clean install. Each option includes high-quality components designed for 69mm valve-length heads and compatible 139QMB/139QMA platforms. Explore key specs, what to expect from performance increases, and how to choose the right kit for your ride.
Summary of chosen products:
- KYMLAA 100cc Big Bore Kit (69mm Valve) – Upgrades without EGR for increased RPM and power
- Glixal 100cc Big Bore Kit with Valve Head Assembly (69mm) – Large valves for more flow
- TRKIMAL 100cc Big Bore Kit (64mm Valve) – Updated valve size and components
- TRKIMAL 47mm 80cc Big Bore Kit – Compact upgrade option for common 49/50cc engines
- CHUNILLE 50mm Bore Piston Kit for 1P39QMB/139QMB – Solid base upgrade with 64mm head compatibility
KYMLAA 100cc Big Bore Kit for 69mm Valve
This kit upgrades gy6 engines from 50cc/60cc/80cc to 100cc, excluding EGR, to achieve higher RPM and increased top speed. It uses a 69mm valve length version and emphasizes simple installation to minimize downtime.
Glixal GY6 80cc + 100cc Big Bore Kit (69mm Valve)
Includes a 47mm cylinder sleeve and 13mm piston pin hardware. This non-EGR cylinder head version focuses on improved flow with 69mm valve-length heads and is designed for the 139QMB family and related engines.
Glixal 100cc Big Bore Kit With Large Valve Head
Designed for 139QMB/139QMA/147QMD engines, this kit features 18.5/20.5mm large valve cylinder head assembly, enabling more airflow and power. It is compatible with 69mm long-valve-type heads and requires rocker-arm compatibility if your original head uses smaller valves.
Glixal ATMT1-008 80cc Big Bore Kit (47mm)
This kit uses a 47mm cylinder diameter with a 13mm piston pin and high-quality piston rings, delivering a solid upgrade path for 139QMB engines while maintaining a practical install footprint for street scooters and light go-karts.
TRKIMAL 47mm 80cc Big Bore Kit (69mm Valve Length)
TRKIMAL’s 47mm 80cc kit targets 49cc/50cc and 139QMB engines with a 69mm valve-length design. It emphasizes compatibility with a wide range of scooter, ATV, and go-kart platforms, making it a versatile upgrade option for many GY6 builds.
TRKIMAL 100cc Big Bore Kit (64mm Valve)
Upgrade from 50cc/60cc/80cc to 100cc with a 64mm valve-length head. It includes a 6-pin racing CDI, ignition coil, and spark plug compatible components to support higher RPM and sustained performance on 139QMB/moped setups. Installation is designed for straightforward fitment.
hauertzx 50mm Big Bore Kit With 64mm Valves
Offers a 50mm bore with a 64mm valve configuration, including a CDI ignition coil and spark plug. It targets 49cc/50cc engines and is positioned as a high-performance upgrade for 139QMB/139QMA platforms with a comprehensive component set for reliable operation.
CHUNILLE 50mm Bore Piston Kit For GY6 1P39QMB 139QMB
CHUNILLE provides a solid 50mm bore piston kit for GY6 1P39QMB/139QMB engines, with a 64mm valve head compatibility. The kit emphasizes high-quality metal construction and asks for professional installation due to the complexity of these upgrades.
Buying Guide: Key Considerations For Choosing A 1P39QMB Big Bore Kit
- Engine compatibility: Verify bore size (47mm, 50mm, or 100mm) and the corresponding valve-length head (64mm, 69mm, or larger) to ensure fitment with your 139QMB/139QMA platform and your scooter’s overall build.
- Valve sizing and head design: Larger valves boost airflow and power, but may require rocker-arm or head modifications. Check if your kit includes or requires additional components for compatibility.
- Non-EGR vs EGR: Non-EGR designs are common in street machines to simplify installation and ensure compatibility with a wide range of intake configurations; EGR-equipped kits may require additional exhaust and intake considerations.
- Compression, timing, and CDI: Some kits include a racing CDI, ignition coil, and spark plug to support higher RPM ranges. Ensure your ignition and fuel system can safely support increased performance.
- Installation complexity: Some kits are straightforward drop-ins; others demand professional installation or machine work (valve work, rocker arms, head compatibility). Plan for proper labor and tools.
- Durability and warranty: Look for metal-constructed sleeves, high-quality piston rings, and documented durability for daily riding and higher RPM use.
- Intended usage: Choose a kit aligned with your riding style—daily commuting, higher-speed highway cruising, or occasional performance boosts for go-karts or ATVs.
- Maintenance implications: Upgrading displacement can affect fuel economy, clutch wear, and cooling needs. Ensure upgrades are complemented by proper maintenance schedules.
- Support and compatibility: Confirm compatibility with your carburetor sizing, exhaust setup, and any required rocker arms or head arms that may differ across brands.