Upgrading a 49cc scooter with an 80cc big bore kit can unlock more torque, higher top speed, and improved acceleration. This article highlights five popular 80cc kits compatible with GY6 and 139QMB engines, explains what to look for when upgrading, and compares their key benefits. Each kit includes essential components for a reliable install, and all options are designed to work with common Chinese-scooter platforms. Read on to identify the right kit for your ride and riding needs.
| Product | Approx. Bore | Engine Compatibility | Notable Benefit |
|---|---|---|---|
| Glixal ATMT1-008 Performance Big Bore Cylinder Kit | 47mm | GY6 80cc, 139QMB based scooters | Durable piston rings, solid construction |
| Performance Upgrade Big Bore Cylinder Kit | 47mm | GY6 80cc for 49cc/50cc platforms | Easy installation, noticeable power increase |
| Tupo 47mm 49cc/50cc to 80cc Kit | 47mm | GY6 4-stroke, 139QMB variants | Comprehensive top-end rebuild kit |
| GY6 Rebuild Kit – 47mm 80cc Upgrade | 47mm | GY6 family scooters | Valve and cylinder compatibility for upgrades |
| KYmlaa 100cc Big Bore Kit | 47mm bore (100cc class) | GY6 50cc/60cc/80cc platforms | Higher RPM potential and performance |
Glixal ATMT1-008 Big Bore Cylinder Kit
The Glixal ATMT1-008 kit targets 47mm bore with a 13mm piston pin diameter and includes high-quality piston rings for durability. Designed for GY6 80cc and 139QMB-based scooters, it offers a balance of reliability and performance. The standard parts list supports a straightforward install for riders who want a robust upgrade without complex modifications.
Performance Upgrade 80cc Big Bore Kit for GY6
This kit is designed to upgrade a 50cc/49cc engine to 80cc with a 47mm cylinder bore and a 13mm piston pin. It emphasizes easy installation and a noticeable power increase, making it a popular choice for riders who want a straightforward performance boost without major engine work. It aligns well with many common scooter platforms in the 49cc to 50cc range.
Tupo 47mm 49cc/50cc to 80cc Kit
The Tupo kit provides a Top End rebuild set with a 47mm bore suitable for 139QMB and GY6 engines. The package includes cylinder, piston kit, rings, gasket set, valve oil seals, and mounting hardware, making it a convenient all-in-one option for an 80cc upgrade. It’s well-suited for riders who prefer a complete rebuild approach to maximizing performance gains.
GY6 Rebuild Kit – 47mm 80cc Upgrade
This rebuild kit targets the GY6 family with a 47mm bore for an 80cc upgrade, featuring a 69mm valve length. It’s compatible with 49cc/50cc engines and similar platforms, providing a practical path to more power while preserving engine reliability. The included components support a thorough top-end refresh during the upgrade process.
KYmlaa 100cc Big Bore Kit
The KYmlaa 100cc kit presents a larger bore option designed to push a 50cc/60cc/80cc gy6 platform toward 100cc performance. Featuring a 69mm valve length and a complete kit that includes a racing CDI ignition coil and performance spark plug, this option aims for higher RPM and faster acceleration. Installation requires careful tuning to maintain reliability at higher output levels.
Buying Guide: Key Considerations For 80cc Big Bore Upgrades
- Engine compatibility: Confirm your scooter’s engine family (GY6, 139QMB, etc.) and check bore compatibility to avoid mismatched parts.
- Quality and warranty: Look for kits with durable pistons, rings, and gaskets, and consider vendor warranties or return policies for peace of mind.
- Installation complexity: Some kits are straightforward bolt-ons, while others require larger top-end work or jetting and ECU adjustments.
- Fuel and timing tuning: Upgrades can shift air-fuel requirements. Plan for possible carburetor jet changes and ignition timing adjustments to prevent overheating or detonation.
- Reliability versus performance: Higher displacement can increase wear and heat. Ensure cooling capacity and lubrication are adequate for sustained riding.
- Top speed vs. acceleration: A larger bore typically improves torque and mid-range power, but top-speed gains depend on gearing, weight, and aerodynamics.
- Supporting components: Consider upgrading gaskets, studs, centrifugal clutch, and air intake, as these influence overall performance and longevity.
- Legal and warranty considerations: Check local regulations regarding engine upgrades and any impacts on scooter warranty or emissions compliance.
When selecting a kit, compare bore size, piston pin diameter, included components, and whether the package includes a full top-end rebuild. For riders seeking a balanced upgrade, kits that offer easy installation with reliable parts often provide the best long-term value. For those chasing maximum performance, larger kits paired with proper tuning may deliver the most noticeable gains while requiring careful maintenance.