Lexmoto: FMR 125 EFI WY125T-74R-E4, FMX 125 EFI WY125T-108-E4, Vienna 125 EFI WY125T-121-E4, Vienna 125 WY125T-121. A timing chain synchronizes the rotation of the crankshaft and camshaft(s) ensuring proper timing and allows the engine's valves to open and close during each cylinder's firing.