Polini Clutch Spring Set | Honda Dio 139QMB Vespa 50cc

Fine-tune your launch performance and eliminate sluggish low-end takeoff with the genuine Polini Clutch Spring Tuning Set. Designed to fit original factory clutches on 50cc scooters, this complete tuning kit allows you to adjust your clutch engagement RPM to match modified exhausts, big bore cylinders, or sport CVT setups—ensuring your engine revs directly into its ideal powerband before sending power to the rear wheel.

Key Features

• 4-Stage RPM Tuning Suite: Includes twelve (12) color-coded clutch springs across four distinct tension rates (ranging from 4,000 RPM to 7,000 RPM engagement) for precise transmission calibration.
• Improved Holeshot & Acceleration: Stiffer spring rates delay shoe engagement until higher engine RPMs, launching your machine with maximum torque off the line.
• High-Tensile Alloy Construction: Premium spring steel withstands intense thermal expansion and friction load without weakening or losing tension over time.
• OEM Clutch Direct Fitment: Engineered specifically for standard factory clutch shoes utilizing M28 thread clutch nuts and 39mm socket configurations.

Vehicle & Engine Compatibility

This tuning spring kit is built for standard OEM 2-shoe and 3-shoe clutches across 50cc 2-stroke and 4-stroke platforms:

Clutch Nut Verification: This spring kit fits stock/OEM clutch assemblies with an M28 thread holding nut and 39mm rear pulley socket. It will not fit oversized 107mm or 110mm aftermarket racing clutches.

Technical Specifications

• Kit Contents: 12 total springs (3 springs per color / 4 tension levels)
• Engagement Range: 4,000–7,000 RPM tuning levels
• Clutch Nut / Socket: M28 thread / 39mm socket size
• MPN: 245.030
• SKU: 1200-1218
• Origin: Made in Italy

Mechanic's Tip: Use a proper clutch nut tool to safely remove the 39mm central nut. When installing, use needle-nose pliers or a spring hook to fully seat the hooks through the clutch shoe holes. Verify all three shoes retract evenly before reinstalling.

California Prop 65 Warning

• 12 color-coded springs across 4 RPM engagement settings (4k–7k)
• Adjustable clutch engagement for modified exhausts, big bore, or sport CVT setups
• High-tensile alloy spring steel resists heat and tension loss
• Fits OEM clutch assemblies with M28 thread nut and 39mm socket
• Compatible with 139QMB/QMA, Honda Dio, Genuine Scooters, and Vespa/Piaggio 50cc platforms

Kit: 12 springs (3 per level, 4 levels) | RPM Range: 4,000–7,000 RPM | Thread: M28 | Socket: 39mm | MPN: 245.030 | SKU: 1200-1218 | Origin: Italy

Honda Dio 50 (AF18/AF27/AF28/AF34/AF35), Lead 50, Elite 50 SA50; Genuine Buddy 50, Buddy 50 International, Brio 50i, RoughHouse 50, RoughHouse 50 Sport; Piaggio/Vespa Zip 50, Typhoon 50, NRG, ET2, LX 50, S 50; 139QMB/QMA 50cc–80cc engines (fits any engine code with QM or FM)