This follows a meeting of the Superbike Commission - the World Superbike series' rule-making body - during the SWC meeting at Silverstone.
The Superbike Commission has decided to scrap the loophole which has allowed Aprilia to drive the camshafts on the RSV4 World Superbike machines using gears instead of the chains fitted on the production bikes.
The rule had originally read: "The method of cam drive (chain, belt or gears) must remain as on the homologated motorcycle unless a complete kit is available through normal commercial channels."
But the last phrase, "unless a complete kit is available through normal commercial channels" - has been dropped.
So either Aprilia homologates an RSV4 with gear-driven cams fitted standard, or reverts to chain drive.