Rotax 503 fan belt adjustment, adjusting the fan belt on the Rotax 503 aircraft engines.
Belt drive RAR-03 for ROTAX engine (up to 48 kW) whith electric starter - BeltDrive
Ski Doo Rotax 503 Blizzard 5500 Snowmobile Engine Fan Side Shroud Everest | eBay
Fan Belt Compatible with Ski-Doo Everest 440 1974-1979 Size 9.5 x 675 mm Snowmobile Part# 12-38103 OEM# 420-9804-00, 402-0121-00 : Automotive - Amazon.com
HTalk2-EdWilsonOnFanBeltTension - YouTube
for sale^ belt drives for ROTAX, HONDA, Suzuki, Yamaha etc. conversions/ - For Sale and wanted, you got it, I want it - AvidFoxFlyers Forums
Rotax 443 / 503 / 550F fan belt - Wandamotor.com
Rotax fan belt replacemet - YouTube
Rotax 503 Ul Engine Crankcase Parts | Aircraft Spruce