Hoca Minarelli 50cc 2-stroke 1PE40QMB Torque Drive Springs in 1000, 1500 and 2000 RPM Sizes. Sold Individually, select RPM Option from drop-down menu. Please see our Warranty & Returns Policy. Please choose your size from the drop down menu Comes in 1000 RPM, 1500 RPM, or 2000 RPM Inner Diameter: 44mm Hoca Minarelli 50cc 2-stroke 1PE40QMB Torque Drive Springs available in 1000, 1500 or 2000 RPM Sizes" from Hoca Minarelli 50cc 2-stroke 1PE40QMB Torque Drive Springs in 1000, 1500 and 2000 RPM Sizes