Engineworx Crankshaft Bearing and Seal Kit Yamaha YZF/WRF 250 03-21 Engineworx Crankshaft Bearing and Seal Kits are the new price leaders in engine rebuild components. Kits are supplied using NTN bearings made in Japan which are renowned for the supplying many of the leading manufacturers with OEM Materials for their engines. OEM specification seals feature a double lip design with a PTFE contact area to ensure maximum seal life. Engineworx Crankshaft Bearing Kits meet or exceed OEM Specification. Features: NTN Japanese Crankshaft Bearings. Bearings are exact OEM replicas with bearing retainer grooves where necessary. OEM Specification Double Lip Oil Seals with PTFE Contact Area. O-Rings Supplied Where Necessary.