SATO RACING has several options for protecting the engine case on 2019-21 BMW S1000RR:
Timing Hole Plug (part# THP-BMWS120) is a compact Delrin guard for the left or right side. Featuring a beefy Delrin slider puck mounted on a Gold anodized aluminum base that can screw into the access hole on either side of the engine.

Note: Engine case cover is not included. Photos are for reference showing the timing hole plug which is in the middle just above the engine case cover.