Recommended Additional Upgrades
01
Uma Laser Iridium Spark Plug
Improve ignition with Uma Racing Laser Iridium Spark Plug.
03
Uma Racing Engine Oil
Get smoother engine performance with Uma Racing Full Synthetic Engine Oil.
The UMA Racing Torque Spring (1000RPM – Red) is a critical CVT (Continuously Variable Transmission) tuning component for the Yamaha NMAX and Aerox 155. The torque spring (also known as a secondary spring) controls the pressure on the rear pulley, dictating how quickly the transmission “shifts” and how effectively it downshifts when you roll off the throttle.
The 1000RPM (Red) version is generally the “Sport/Street” setting—stiffer than the stock spring but not so stiff that it ruins your fuel economy or top speed.
Key Performance Benefits
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Eliminates Belt Slip: The increased tension ensures the CVT belt is gripped more tightly by the rear pulley, preventing “slipping” during hard acceleration.
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Faster Back-Shift: When you slow down for a corner and then hit the gas, a stiffer spring forces the transmission to “downshift” to a lower gear ratio faster, giving you better overtaking power.
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Improved Low-to-Mid Response: It holds the “lower gear” slightly longer, allowing the engine to stay in its power band during acceleration.
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Heat Fatigue Resistance: UMA uses high-fatigue silicon-manganese steel, meaning the spring won’t “soften” or lose its tension even after hours of high-heat riding.
Why Choose the 1000RPM (Red) over 1500RPM?
| Spring Strength | Best Use Case | Character |
| Stock | Commuting | Soft, smooth, focuses on fuel economy. |
| 1000RPM (Red) | Daily Sport / Touring | Snappier acceleration without excessive engine screaming. |
| 1500RPM (Blue) | Racing / Big Bore | Very aggressive; keeps RPMs very high; can lower top speed. |
Technical Specifications
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Rating: 1000 RPM (tension equivalent)
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Color: Red (UMA’s signature color coding for 1000RPM)
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Material: High-grade Silicon Manganese Steel
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Compatibility: * Yamaha NMAX 155 (V1 & V2)
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Yamaha Aerox 155 / NVX 155 (V1 & V2)
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Often fits other Yamaha 155cc BlueCore scooters
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Tuning Tip: The “Balanced” CVT
A torque spring should never be changed in isolation for the best results. To get the most out of the Red 1000RPM spring, consider your Roller Weights:
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If your bike feels like it’s “struggling” to reach top speed after installing this spring, you may need to use slightly heavier roller weights to help push the belt against the spring’s tension.
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This spring pairs perfectly with the UMA Racing High Speed Pulley Kit for a complete CVT overhaul.
Maintenance Note: When installing, it is highly recommended to clean the rear pulley and apply fresh high-temp CVT grease to the torque cam pins to ensure smooth sliding motion.
FAQs
What does a torque spring do?
It controls rear pulley response and belt tension in the CVT system.
Is 1000RPM good for daily riding?
Yes, it’s a popular mild performance upgrade for quicker response.
Will it reduce top speed?
Usually minimal impact when matched with correct roller setup.
