Answering what to buy for a 150cc big bore upgrade, these kits expand displacement, improve airflow, and boost power for everyday riding and performance-focused builds. This guide highlights five well-matched options for GY6 150cc engines and similar 4-stroke setups. Ideal buyers include scooter and ATV enthusiasts, small-shop mechanics, and DIY riders seeking reliable top-end upgrades. Below is a quick buyer’s table to compare select kits at a glance.
| Product | Best For | Important Note |
|---|---|---|
| TRKIMAL Complete GY6 Cylinder Head Rebuild Kit | Shop or personal rebuilds needing a full kit | 57.4mm bore; compatible with many GY6 125/150 engines |
| GOOFIT 57.4mm Big Bore Cylinder Kit | Call for a straightforward 150cc upgrade | Includes complete cylinder assembly; verify 57.4mm sizing |
| GOIRTUTSS 57.4mm Bore Complete Kit | Broad compatibility across Taotao, Kymco, Baja and more | Requires crankcase bore work for some bikes |
TRKIMAL 57.4mm GY6 Big Bore Kit
The TRKIMAL kit targets GY6 4-stroke engines around 125cc to 150cc, featuring a 57.4mm bore and a full set of parts suitable for motorcycle maintenance shops, parts retailers, and DIY riders. It is designed for easy installation within a shop or home workshop context, making it a practical option for those who want a complete rebuild path. Best for a user who values a full parts bundle and a straightforward upgrade path without hunting for individual components.
Best for: Shops and home garages needing a complete kit that covers gasket sets, valves, and related components. Better for: users who want a budget-friendly, all-in-one solution. Choose this if: you prefer a ready-to-install package with standard GY6 compatibility. Caution: verify engine compatibility with 57.4mm bore and ensure your crankcase can accommodate the kit without additional machining.
GOOFIT 57.4mm Big Bore Cylinder Kit
The GOOFIT kit provides a 57.4mm bore with piston components designed for 150cc class GY6 engines (157QMJ lineage). It is a practical option for riders who want a precise bore size and a complete rebuild kit. It’s best for users who need a direct replacement that aligns with common 150cc Chinese scooter engines. The kit is better for those who want a simpler, drop-in upgrade without extra machining beyond standard maintenance tasks. Caution: confirm the specific model fitment and piston pin sizes before ordering to avoid size mismatches.
GOIRTUTSS 61mm Upgrade for 150cc GY6 Family
This kit bumps the bore to 61mm, offering a higher power ceiling for 150cc class GY6 engines. It’s compatible with multiple Chinese scooter families (Taotao, Kymco, Baja, Sunl, etc.) and includes a full cylinder head, piston assembly, gaskets, and a complete gasket set. Best for: riders seeking a notable performance increase and a robust, durable build. Better for: those who can perform minor crankcase bore work or machine shop support. Caution: not suitable for engines requiring a 57.4mm bore and be aware of outer cylinder size changes which may require case modifications.
GallopingKnight 57.4mm Bore Kit With Gaskets
The GallopingKnight kit centers on a 57.4mm bore for 150cc 4-stroke GY6 engines, including gaskets and a piston rebuild. It emphasizes easy installation, corrosion resistance, and durable wear resistance. Best for: riders seeking a dependable upgrade with compatible ska—great for scooters, mopeds, go-karts, and ATVs that use the 57.4mm bore. Better for: those who value a balanced blend of durability and cooling efficiency. Caution: verify fit with your specific model’s cylinder head and gasket compatibility; some handlebars may require additional gasket alignment for a leak-free seal.
LK LEAPING KNIGHT 63.8mm Upgrade (61mm to 63.8mm Outer)
This LK LEAPING KNIGHT offering focuses on a larger 61–63.8mm outer cylinder size, promoting a higher displacement path (61mm bore core with outer 63.8mm). It’s designed for 125cc/150cc GY6 engines and notes the need to bore the crankcase to fit most bikes, often requiring machine shop work. Best for: builders aiming for a substantial power up and who have access to machining tools. Better for: those who want a more aggressive upgrade and don’t mind additional prep work. Caution: requires professional bore work and careful alignment to maintain engine integrity and sealing.
LK LEAPING KNIGHT 180cc 62mm Kit
This 180cc kit for GY6 engines uses a 62mm bore to deliver noticeable performance gains over standard 150cc configurations, with a focus on high-strength aluminium components and effective heat dissipation. Best for: riders who want a significant displacement increase and stronger heat management for sustained higher RPMs. Better for: those who can support more extensive installation work and cooling assessment. Caution: verify compatibility with your bike’s case and head design; this kit often requires more extensive engine work and may affect reliability if not installed properly.
Buying Guide
Key considerations for selecting a 150cc big bore kit include bore size, engine compatibility, and installation requirements. The most common size shown here is 57.4mm, which fits many GY6 150cc engines, but some kits offer 61mm or 62mm options that require case modification. Consider these questions:
- What is my engine family and bore size? Verify if your engine is a 157QMJ, 152QMI, or another variant to avoid mismatches.
- Do I have access to machine shop capabilities if the kit requires crankcase bore work? Some kits explicitly require this.
- Is the kit a full rebuild set or a partial upgrade? Full kits simplify installation but may be more expensive.
- What is the cooling and lubrication design of my scooter or ATV? Higher displacement often demands improved cooling solutions.
- What components are included in the kit? Look for piston, rings, gaskets, and head components to ensure a complete upgrade.
- Will I need additional modifications (intake, exhaust, or ECU tuning) to reap the full benefit? Some engines benefit from tuning adjustments.
FAQ
- What is a big bore kit? A big bore kit increases engine displacement by enlarging the cylinder bore to produce more power and torque.
- Do I need machining to install a 61mm or 62mm bore kit? Yes, many kits require crankcase or cylinder head modification to fit properly, often needing a machine shop.
- Will a 150cc big bore kit fit my 125cc engine? Fit depends on engine model and bore size; always verify compatibility with your model’s specifications.
- Is a complete rebuild kit better than separate parts? For many users, a complete kit simplifies installation and reduces missing components.
- Can I install a big bore kit myself? It’s feasible for skilled DIYers with the right tools, but consider professional help for machining and tolerances.
- What kind of maintenance follows a big bore upgrade? Expect more demanding cooling needs, regular oil checks, and periodic inspection of seals and gaskets.