NCY Performance Adjustable Sheave Clutch Pulley - GY6 & Navi idle and O-ring

and O-ring

It provides just enough extra tension to prevent belt slip without forcing the engine into excessively high RPMs during cruising

You will be glad you did every time you fill your tires

1 - 83111 Grommet

NCY Performance Adjustable Sheave Clutch Pulley - GY6 & Navi idle and O-ringMaximize Your CVT Performance: NCY Adjustable Torque Driver Eliminate mid range "flat spots" and take full control of your powerband with the NCY Secondary Sliding Sheave. Engineered as a high performance alternative to the linear factory pulley, this "Torque Driver" features dual machined ramp angles. This allows you to choose between an aggressive curve for instant "off the line" snap or a progressive curve for smoother, high velocity cruising.