Malossi 70cc Big Bore Cylinder Kit: Genuine / Minarelli 2T

Transform your sluggish 50cc into a high-torque street machine with the legendary Malossi 70cc Cast Iron Sport Cylinder Kit. Precision-engineered and cast in Italy, this air-cooled (AC) big-bore kit is the industry benchmark for riders demanding a massive bump in acceleration, hill-climbing torque, and mid-range power without sacrificing daily reliability. By optimizing internal port timing and expanding the bore diameter, Malossi delivers a broad, forgiving powerband that pairs beautifully with stock or sport-class setups.

Premium Italian Engineering Features

• Wear-Resistant Cast Iron Bore: Engineered from high-tensile, thermal-stable cast iron alloys capable of withstanding extreme daily operation and structural stress.
• Optimized Port Architecture: Features recalculated transfer and exhaust port geometries designed to maximize scavenging efficiency and low-to-mid range torque.
• High-Compression Cylinder Head: Includes a dedicated, die-cast aluminum cylinder head designed to optimize squish clearance and maximize combustion efficiency.
• Low-Friction Dual-Ring Piston: Ships with a premium light-alloy piston assembly utilizing two high-strength compression rings for reliable sealing and extended top-end life.

Comprehensive Fitment & Wrist Pin Guide

This cylinder kit is engineered strictly for horizontal, air-cooled (AC) 2-stroke Minarelli and Minarelli-clone engine blocks equipped with a 10mm wrist pin:

CRITICAL WRIST PIN FITMENT WARNING: This kit includes a 10mm wrist pin piston. While standard Genuine 50cc and Yamaha Zuma Bugeye models use a 10mm pin from the factory, some vintage European models, custom aftermarket cranks, or older Yamaha "Prebug" (1989–2001) vertical models utilize a 12mm wrist pin. Always measure your crankshaft small-end needle bearing layout before ordering.

Technical Specifications

• Displacement Capacity: 70cc (Sport Class Baseline)
• Cylinder Bore Diameter: 47mm
• Wrist Pin Diameter: 10mm
• Cooling Configuration: Air-Cooled (AC) Only
• Material Composition: Heavy-Duty Cast Iron Cylinder / Aluminum Head
• Manufacturer Part Number: 4614340 (46 14340)
• Country of Origin: Italy (IT)

Carburetor Tuning Note: Running a 70cc kit requires immediate fuel calibration. You MUST up-jet your factory carburetor main jet (typically an increase of 10–15% in size) or pair this kit with an upgraded carburetor layout to prevent running dangerously lean and causing immediate structural heat seizure.

Pro Maintenance Tip: Always practice a proper heat-cycle break-in procedure during the first 150–200 miles. Mix a light 50:1 ratio of high-quality synthetic 2-stroke oil directly into your first full tank of gas to guarantee extra top-end lubrication while the new rings seat to the cast iron walls.

NOTE: Please check your wrist pin size before ordering. This kit comes with a 10mm wrist pin piston. If your scooter has a 12mm wrist pin, you'll need to also order this piston.

Replacement 10mm pistons are available here.

Replacement rings are available here.

---

Notice: This product is intended for off-road and racing use only. Not legal for use on pollution-controlled vehicles in California or on public roads. Check local laws before installing. Performance upgrades are not covered under warranty.

SKU: M4614340
Vendor: Malossi
Category: Engine Parts / Cylinder Kits

California Prop 65 Warning: www.P65Warnings.ca.gov