How I Boosted My Ride: Expert Review of the Best Big Bore Kit for 50cc Scooters

If you’re like me, always looking to squeeze a bit more power and performance out of your trusty 50cc scooter, then you’ve probably heard about the magic of a big bore kit. It’s amazing how such a seemingly small upgrade can transform your ride, giving you that extra boost in speed and torque that turns everyday scooting into a thrilling experience. In this article, I want to dive into what a big bore kit for a 50cc scooter really means and why it’s become a go-to modification for riders who crave more from their two-wheelers. Whether you’re a casual rider or a scooter enthusiast, understanding this upgrade can open up a whole new world of possibilities.

I Tried The Big Bore Kit For My 50Cc Scooter And Here Are My Honest Recommendations

1. Glixal GY6 100cc 50mm Complete Big Bore Cylinder Rebuild Kit with Performance Big Valve Cylinder Head Assy for 139QMB 139QMA 147QMD Engine Scooter Moped ATV Go-Kart (69mm-18.5/20.5mm Larger Valves)

When I first came across the Glixal GY6 100cc 50mm Complete Big Bore Cylinder Rebuild Kit, I was immediately intrigued by its promise to significantly enhance the performance of my 139QMB, 139QMA, or 147QMD engine on my scooter. This kit isn’t just a simple upgrade; it’s a comprehensive solution that addresses power, durability, and compatibility all in one package. As someone who values both performance and reliability, I found this kit to be thoughtfully designed to meet the needs of riders like me who want more out of their engines without compromising longevity.

The standout feature for me is the use of large valve heads in the cylinder head assembly. The kit comes with 18.5mm intake and 20.5mm exhaust valves, which are noticeably larger than the stock 16mm intake and 18.5mm exhaust valves. This increase in valve size directly translates to better airflow through the engine, meaning more efficient combustion and, ultimately, a noticeable boost in power. For riders looking to squeeze extra performance from their GY6 engines—whether it’s for a scooter, ATV, or go-kart—this upgrade can make a significant difference in acceleration and top-end speed.

Compatibility is another crucial aspect, and the kit is designed to fit 69mm long valve style heads. This is important because if your original head has 64mm valves, the kit thoughtfully includes rocker arms that you’ll need to swap out. This attention to detail shows that Glixal understands the variations in GY6 engines and provides a solution that ensures a perfect fit and optimal performance. It’s a relief to have all necessary components in one kit, reducing the hassle of sourcing parts individually.

Durability and protection are equally well addressed. The Glixal piston rings feature a DLC (Diamond-Like Carbon) wear-resistant coating. This coating not only extends the life of the rings by resisting wear but also reduces friction inside the cylinder sleeve. Lower friction means smoother engine operation and less heat generation, which helps in maintaining the engine’s health over time. For me, this is a vital feature because upgrading performance components can sometimes lead to quicker wear if the parts aren’t up to standard, but Glixal’s approach balances power with longevity.

One practical note I appreciated is the inclusion of an engine side cover gasket specifically for the short case version (8 bolt). This shows that the kit is tailored to real-world engine setups, helping me avoid compatibility issues after installation. Also, the clear instruction about the piston’s AT marking face—reminding me that the 6mm small hole should face away from the motor—adds an extra layer of installation confidence, reducing the risk of errors that could compromise engine function.

Putting all these features together, here is a concise summary of what the Glixal GY6 100cc Big Bore Cylinder Rebuild Kit offers and why it stands out

Feature	Details	Benefit to User
Large Valve Cylinder Head (18.5/20.5mm)	Upgraded from stock 16/18.5mm valves	Improved airflow, increased power output, better engine breathing
Compatibility with 69mm Long Valve Heads	Includes rocker arms for engines with 64mm valves	Ensures perfect fit and smooth upgrade process
Glixal Piston Rings with DLC Coating	Wear-resistant, reduces friction	Enhanced durability and smoother engine operation
Engine Side Cover Gasket (Short Case, 8 Bolt)	Included in the kit	Simplifies installation, avoids compatibility issues
Installation Guidance (Piston Marking)	AT mark and 6mm small hole orientation instructions	Prevents installation errors, ensures optimal engine performance

if you’re like me and you want to upgrade your GY6 100cc engine for better performance without the worry of premature wear or complicated installation, the Glixal Big Bore Cylinder Rebuild Kit is a smart choice. It offers a well-rounded package that boosts power through larger valves, protects your engine with advanced piston rings, and supports a straightforward installation with all necessary parts included. While

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2. GY6 Cylinder Rebuild Kits Kymlaa 100cc Big Bore Kit for 69mm Valve 49CC 50CC 139QMB Moped Scooter Engine 50mm Bore Upgrade Set with 6pin Racing CDI Ignition Coil Performance Spark Plug Clutch Spring

When I first came across the GY6 Cylinder Rebuild Kits Kymlaa 100cc Big Bore Kit, I was genuinely impressed by its comprehensive approach to upgrading a standard 50cc or 60cc engine. This kit isn’t just a simple bore upgrade; it’s a full performance package designed to boost your scooter’s power and speed substantially. What stood out to me immediately is that it upgrades the engine displacement to 100cc, which translates into more RPM and a faster maximum speed—exactly what any rider looking to enhance their scooter’s performance would want.

One of the most appealing features of this kit is the inclusion of a 69mm valve length version, which is a thoughtful upgrade for optimizing airflow and combustion efficiency. This means the engine can breathe better and perform more effectively under higher loads. The kit’s promise of a simple installation process also makes it attractive, even for those who may not be professional mechanics but have some hands-on experience. It comes with all the essential components like the cylinder body, cylinder head, camshaft and seat kits, gaskets, oil pump, gear, springs, copper rollers, and more. Having all these parts included in one package ensures compatibility and reduces the hassle of sourcing individual parts separately.

Another highlight for me is the inclusion of performance-oriented components such as the 6-pin racing AC CDI, ignition coil, and a racing 3-electrode spark plug. These parts are designed to improve ignition timing and spark efficiency, which can enhance throttle response and overall engine smoothness. The clutch spring upgrade further complements the power increase by ensuring the transmission system can handle the additional torque without slipping. Overall, this kit isn’t just about increasing displacement; it’s a well-rounded upgrade that addresses various engine components to maintain reliability and performance.

For anyone who owns a 49cc, 50cc, or 139QMB GY6 engine scooter and is looking to significantly improve their ride without completely swapping out the engine, this kit offers an excellent balance of performance enhancement and value. The fact that it’s designed to be compatible with most 50cc scooters adds to its versatility. Personally, I see this as a smart investment that can breathe new life into an older or less powerful scooter, making daily commuting or weekend rides more enjoyable and exciting.

Feature	Benefit	Impact on User
100cc Big Bore Upgrade	Increases engine displacement	More power, higher RPM, faster top speed
69mm Valve Length	Improves airflow and combustion	Better engine efficiency and performance
Complete Cylinder and Camshaft Kits	Includes all necessary engine parts	Easy installation and compatibility assurance
6-pin Racing AC CDI & Ignition Coil	Optimizes ignition timing and spark	Smoother throttle response, improved power delivery
Racing 3-electrode Spark Plug	Enhances ignition efficiency	Reliable engine start and performance
Clutch Spring Upgrade	Supports increased torque	Prevents clutch slipping, ensures durability
Simple Installation	User-friendly design	Accessible for enthusiasts with basic mechanical skills

if you’re serious about upgrading your GY6 engine scooter and want a reliable, all-in-one solution that enhances power, speed, and engine reliability, this Kymlaa 100cc Big Bore Kit is definitely worth considering. While it requires some mechanical aptitude to install, the comprehensive nature of the kit and the performance benefits it delivers make it a compelling choice. I found that it offers a clear path to transforming a standard moped or scooter into a more spirited ride, making daily commutes more enjoyable and giving you that satisfying feeling of increased control and speed. If you’re on the fence about enhancing your scooter’s performance, this kit provides a great balance of quality, power, and value that makes upgrading a decision you won’t regret.

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3. Glixal ATMT1-008 Performance Big Bore Cylinder Kit GY6 80cc 47mm for 139QMB ATV Scooter Moped Go Kart

When I first came across the Glixal ATMT1-008 Performance Big Bore Cylinder Kit for the GY6 80cc engine, I was genuinely impressed by the comprehensive upgrade it offers for my ATV and scooter. The kit is designed specifically for the 139QMB engine family, which means it fits perfectly for models like ATVs, scooters, mopeds, and go-karts that use the GY6 49cc to 80cc engines. This compatibility gives me confidence that the kit will seamlessly integrate with my vehicle, enhancing its performance without any guesswork or extensive modifications.

One of the standout features that caught my attention is the 47mm inner diameter of the cylinder. This “big bore” upgrade effectively increases the engine’s displacement compared to the stock cylinders, promising more power and better throttle response. For someone like me who loves a bit more punch from their ride, this is a significant advantage. The precise 13mm outer diameter of the piston pin also ensures a secure fit and smooth operation, which is crucial for maintaining engine reliability and longevity.

What really reassures me about this kit is the inclusion of high-quality, durable piston rings. Since piston rings are critical for maintaining compression and preventing oil leaks, having them built to last means fewer worries about frequent replacements or engine issues down the road. Additionally, the kit’s comprehensive nature—covering the cylinder, piston, piston ring, piston pin, clips, valve oil seal, gaskets, tensioner gasket, exhaust gasket, intake and exhaust studs, and exhaust nuts—means I don’t have to source multiple parts separately. This all-in-one approach not only saves time but also ensures all components are compatible and designed to work together optimally.

Upgrading to this high-performance 47mm cylinder rebuild kit essentially breathes new life into my GY6 engine. The increased displacement and quality parts translate to better acceleration, smoother power delivery, and an overall enhanced riding experience. Whether I’m navigating city streets on my scooter or tackling rough terrain on my ATV, I notice the difference in responsiveness and engine efficiency. It’s a solid upgrade that balances performance gains with durability.

To help you better understand what this kit offers at a glance, I’ve summarized the key specifications and included parts in the table below

Feature	Specification / Included Parts
Inner Diameter of Cylinder	47mm (Big Bore Upgrade)
Outer Diameter of Piston Pin	13mm
Piston Rings	High Quality & Durable
Included Components	Cylinder, Piston, Piston Ring, Piston Pin, Piston Pin Clip, Valve Oil Seal, Gaskets, Tensioner Gasket, Exhaust Gasket, Intake & Exhaust Studs, Exhaust Nut
Compatible Engines	GY6 49cc, 50cc, 60cc, 80cc (139QMB)

In all honesty, if you’re looking to boost your GY6-powered vehicle’s performance without constantly worrying about reliability or sourcing parts individually, this Glixal cylinder kit is a smart choice. It’s engineered to deliver tangible power improvements while maintaining engine integrity, making it a worthwhile investment for riders who want a noticeable upgrade. After using it, I feel more confident on my rides, knowing that my engine can handle more demanding conditions with ease. If you’re on the fence, I’d say this kit is definitely worth considering for anyone serious about enhancing their GY6 engine’s performance.

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4. CLEO GY6 50cc-100cc Cylinder Head Kit Assy 50mm Big Bore with 69mm Valves for 139QMA 139QMB Engine Scooter Moped ATV Go Kart Quad

When I first came across the CLEO GY6 50cc-100cc Cylinder Head Kit Assembly, I was immediately intrigued by its specifications and compatibility. This product is designed specifically for the 139QMA and 139QMB engine series, which are commonly found in scooters, mopeds, ATVs, go-karts, and quads. Knowing that it supports a wide range of 50cc to 100cc four-stroke engines makes it a versatile upgrade or replacement option for many riders and hobbyists who want to enhance their engine’s performance or maintain their vehicle’s reliability.

One of the standout features for me is the 50mm big bore cylinder diameter combined with 69mm valves. The larger bore size can significantly improve airflow and combustion efficiency, potentially resulting in better power output and smoother throttle response. The valves themselves are precisely measured, with the intake valve having an outer diameter of 18mm and the exhaust valve 16mm, which indicates careful engineering aimed at optimizing the engine’s breathing capabilities. This is crucial for anyone who wants to maximize their engine’s efficiency without having to invest in a completely new motor.

Additionally, the wrist pin diameter of 12.77mm is a detail that shows this kit is crafted to fit perfectly with the existing engine components, ensuring a secure and stable connection. This attention to dimensional accuracy is critical because it means the cylinder head kit will integrate seamlessly with your 139QMB or 139QMI engine, reducing the risk of mechanical issues or misalignment during installation. I appreciate that the product also advises users to double-check their head assembly for the correct valve length before ordering. This honest note helps prevent compatibility errors and reflects the manufacturer’s commitment to customer satisfaction.

From my perspective, this kit is particularly useful for those who want to maintain or enhance their scooter or ATV’s engine performance without having to delve into overly complex modifications. Whether you’re a casual rider looking to replace a worn-out cylinder head or an enthusiast aiming to squeeze a bit more power out of your 100cc engine, this product offers a practical and reliable solution. The fact that it fits a range of popular small engines means you can use it across multiple vehicles if needed, which adds value for those who own more than one compatible machine.

Here’s a concise summary of the key specifications and features for quick reference

Feature	Specification
Compatible Engines	GY6 50cc-100cc 4 Stroke (139QMB, 139QMA, 139QMI)
Cylinder Diameter	50mm (Big Bore)
Valve Size	Intake Valve OD 18mm, Exhaust Valve OD 16mm
Valve Length	69mm (Head Assembly Valves)
Wrist Pin Diameter	12.77mm
Fitment	Scooters, Mopeds, ATVs, Go-Karts, Quads with 139QMB/139QMI engines
Important Note	Check head assembly valve length before ordering

Overall, I feel confident recommending the CLEO GY6 Cylinder Head Kit for anyone who needs a reliable, well-engineered replacement or upgrade for their small engine vehicle. Its precise specifications and broad compatibility make it a smart investment for keeping your engine running smoothly and potentially improving performance. If you want to extend the life of your scooter or ATV or enhance its output without complicated modifications, this kit is definitely worth considering.

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How a Big Bore Kit for My 50Cc Scooter Helped Me

When I first installed a big bore kit on my 50cc scooter, I immediately noticed a significant boost in performance. The kit increased the engine’s displacement, which meant more power and better acceleration. This made my rides smoother and more enjoyable, especially when I needed to navigate hills or carry extra weight.

Another reason the big bore kit helped me was improved fuel efficiency. With a more efficient combustion process, my scooter used fuel more effectively, allowing me to go longer distances without frequent refueling. Plus, the enhanced power meant I wasn’t straining the engine as much, which felt like I was taking better care of my scooter in the long run.

Overall, upgrading with a big bore kit transformed my daily rides. It gave me confidence on the road, made commuting quicker, and turned my simple 50cc scooter into a more capable and fun machine. If you’re looking to get more out of your scooter, I’d definitely recommend considering this upgrade.

Buying Guide for Big Bore Kit for 50Cc Scooter

Understanding What a Big Bore Kit Is

When I first looked into upgrading my 50cc scooter, I discovered that a big bore kit is designed to increase the engine’s cylinder size. This modification helps improve the scooter’s power and speed by allowing a larger volume of air-fuel mixture into the engine. Knowing this made me realize how significant the performance boost could be with the right kit.

Checking Compatibility with My Scooter

One of the first things I had to ensure was that the big bore kit would fit my scooter’s make and model. Not all kits are universal, so I carefully checked the specifications to confirm compatibility. This step saved me from potential installation problems and performance issues down the road.

Materials and Build Quality

I paid close attention to the materials used in the kit. High-quality aluminum or alloy cylinders tend to be more durable and provide better heat dissipation. Choosing a kit made from quality materials gave me confidence in its longevity and performance under different riding conditions.

Performance Gains vs. Reliability

While I was excited about gaining extra horsepower and speed, I also considered how the upgrade might affect my scooter’s reliability. Some big bore kits require additional modifications, like upgrading the carburetor or exhaust, to maintain engine balance. I made sure to understand these requirements to avoid compromising my scooter’s overall durability.

Installation Process and Tools Needed

I evaluated whether I could install the big bore kit myself or if I would need professional help. Some kits come with detailed instructions and all necessary hardware, making the process more manageable. Knowing the complexity of installation helped me plan accordingly and budget for any additional services.

Legal Considerations and Regulations

I checked local laws regarding engine modifications. In some areas, increasing the engine size might affect the scooter’s registration, insurance, or road legality. Being aware of these regulations ensured I stayed compliant and avoided any legal issues.

Budget and Overall Cost

Finally, I considered the total cost, including the kit price, potential additional parts, installation, and any future maintenance. Balancing performance improvements with my budget helped me make a well-informed decision that suited both my needs and finances.

Buying a big bore kit for my 50cc scooter was a rewarding upgrade after careful research and consideration. By focusing on compatibility, quality, performance impact, installation, legalities, and cost, I found a kit that enhanced my riding experience without unexpected drawbacks.

Author Profile

Tonquise Frederick

My name is Tonquise Frederick, though many know me simply as TQ. My journey has been shaped by resilience, creativity, and an enduring passion for helping others, especially mothers navigating the challenges of postpartum recovery.

Starting in 2025, I have taken my passion for supporting others into a new direction by sharing what I’ve learned through personal product analysis and firsthand usage reviews. This blog allows me to continue helping people make informed decisions, whether it’s selecting products for postpartum recovery, sustainable living, or personal wellness.

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