Variator rollers

How it works

Rollers are the small weighted cylinders that make a scooter's variator work. Sitting in grooves in the variator's moving half, they are thrown outward by centrifugal force as revs rise, which pushes the two halves together and makes the belt ride on a larger diameter: the ratio gets taller, as if you were shifting up. Their weight shapes how the scooter behaves: lighter rollers favour acceleration, heavier ones top speed, within the manufacturer's limits. With time and heat, rollers wear flat spots: they stop rolling, stick, and the transmission becomes uneven, with sluggish acceleration, lower top speed and sometimes clunks. Rollers are replaced as a full set, often together with the belt and sliders. The job is done with the transmission cover off, using a tool to hold the variator.

Maintenance tips

• ✓Check the rollers at every belt change: flat spots mean they must be replaced.
• ✓Always replace rollers as a full set, with the weight specified for your scooter.
• ✓Clean the variator without greasing it, unless the manufacturer says otherwise.
• ✓While it is apart, check the belt, sliders and moving half.
• ✓Torque the variator nut to the value in the manual.