Product Description

NCY 61mm 171cc Big Bore Cylinder Kit – No Case Machining Required

Fits GY6 125cc/150cc A-Block Engines (54mm Stud Spacing Only) | Made in Taiwan

Unlock the full performance potential of your GY6 engine with the NCY 61mm 171cc Big Bore Cylinder Kit. Engineered as one of the only true bolt-on 171cc upgrades available in the United States, this premium kit is specifically designed for 54mm A-Block GY6 engines and features a unique 62.7mm outer cylinder skirt that eliminates the need for crankcase machining on compatible engines.

Unlike most 61mm big bore kits that require the engine cases to be bored or ground to accommodate a 65mm cylinder sleeve, the NCY kit utilizes a specially designed slim-skirt cylinder that drops directly into compatible A-Block crankcases with a minimum 62.9mm crankcase bore opening. This makes it one of the easiest and most effective ways to increase engine displacement to approximately 171.3cc without expensive machine work.

To further improve engine performance, NCY includes a lightweight cut-down (short-skirt) cast aluminum racing piston that reduces reciprocating mass, allowing the engine to rev quicker while improving throttle response, acceleration, and overall power output.

Whether you're building a high-performance street scooter, buggy, ATV, or go-kart, the NCY 171cc kit delivers a massive increase in torque and horsepower while maintaining excellent reliability.

Why Upgrade to 171cc?

Increasing displacement from a stock 125cc or 150cc engine to approximately 171.3cc dramatically improves overall engine performance.

Performance Benefits

• Increases displacement to approximately 171.3cc
• Massive increase in low-end torque
• Faster acceleration
• Improved hill-climbing power
• Stronger mid-range performance
• Higher top-speed potential with proper tuning
• Improved throttle response
• Greater horsepower throughout the RPM range
• Excellent foundation for high-performance engine builds

NCY Performance Advantages

True Bolt-On Design

Unlike most 61mm cylinder kits that require cutting or boring the engine cases, the NCY cylinder features a special slim-skirt design that fits compatible engines without machining.

Lightweight Racing Piston

The included short-skirt cast aluminum piston reduces reciprocating weight, allowing:

• Faster engine response
• Higher RPM capability
• Reduced internal friction
• Improved acceleration

Superior Cooling

The aluminum piston and precision-engineered cylinder design help improve heat management for more consistent performance during aggressive riding.

Premium Manufacturing

Manufactured in Taiwan using high-quality materials and strict machining tolerances for outstanding durability and long service life.

Package Includes

• NCY 61mm Cylinder
• Lightweight 61mm Cast Aluminum Racing Piston
• Complete 61mm Piston Ring Set
• Wrist Pin
• Wrist Pin Circlips
• Compression Base Gaskets
• Steel Head Gasket
• Complete Top-End Gasket Kit

Everything needed to complete your top-end installation.

Specifications

Brand: NCY

Country of Manufacture: Taiwan

Cylinder Bore: 61mm

Engine Displacement: Approximately 171.3cc

Cylinder Type: Cast-Iron Cylinder

Piston Material: Lightweight Cast Aluminum

Piston Style: Short-Skirt Performance Design

Piston Ring Configuration: 5-Piece Ring Set

Ring Thickness: 1mm / 1mm / 2mm

Outer Cylinder Sleeve Diameter: 62.7mm

Minimum Crankcase Bore Required: 62.9mm

Cylinder Height (Without Sleeve): 69.3mm

Overall Cylinder Height: 90mm

Wrist Pin: 48mm × 15mm

Engine Compatibility

Designed specifically for 54mm Stud Spacing A-Block GY6 engines.

Compatible engine codes include:

• 157QMJ
• 152QMI
• 1P57QMJ
• BN157QMJ

Always verify your engine measurements before purchasing.

Common Vehicle Applications

Compatible with many GY6-powered vehicles including:

Scooters

• TaoTao
• Wolf
• Ice Bear
• Bintelli
• Peace Sports
• ZNEN
• SSR
• Kymco 125/150 models

Go-Karts & Buggies

• Hammerhead 150
• TrailMaster 150
• Yerf-Dog
• Carter Talon

Many additional GY6-powered applications may also be compatible.

Recommended Supporting Upgrades

To maximize the performance of this 171cc engine build, NCY recommends:

• NCY 61mm Big Valve Cylinder Head
• Performance Camshaft
• Larger Performance Carburetor
• Performance Intake Manifold
• High-Flow Exhaust System
• Upgraded CDI
• Performance Ignition Coil
• Heavy-Duty CVT Components

Proper carburetor re-jetting is strongly recommended. This kit requires a significantly richer fuel mixture than stock to prevent overheating and maximize performance.

Important Fitment Information

THIS KIT FITS ONLY:

✔ 54mm Stud Spacing A-Block GY6 Engines

THIS KIT WILL NOT FIT:

❌ 57mm Stud Spacing B-Block Engines

❌ QMK / K-Block Engines

❌ Genuine Buddy 125 (Use NCY Part #1100-1287 instead)

❌ Any engine with less than 62.9mm crankcase bore clearance

Always measure your crankcase opening with a caliper before purchasing.

If your crankcase opening measures less than 62.9mm, machining will be required.

Installation Notes

• Verify 54mm stud spacing before ordering.
• Measure crankcase bore before installation.
• Professional installation is recommended.
• Proper carburetor jetting is required.
• Check piston-to-valve clearance when using aftermarket cylinder heads.
• Some stock cylinder heads may not fit this kit.
• Break in the engine properly before sustained high-RPM operation.

Why Choose NCY?

NCY Performance is one of the most respected manufacturers of scooter performance parts, producing premium components designed for reliability, performance, and precision fitment. Their innovative slim-skirt 61mm cylinder design makes this one of the easiest 171cc upgrades available for compatible GY6 engines.

Important Notice

This performance cylinder kit is intended for off-road, racing, or closed-course competition use where permitted by law. Always verify engine compatibility and measurements before purchasing. Proper tuning, carburetor jetting, and supporting performance components are essential for safe operation and maximum engine performance.