26 X 23.3 (6). MAIN SEAL & GASKET (not shown). Yamaha Rd 250 350 400 Air Cooled Dry Clutch Cover Conversion Kit. The seller is fondseca and is located in Heathfield. 26 X 23.2 (10). 22.2 X 20.4 (6). The seller is fondseca and is located in Heathfield.