Will a Yamaha yz250f plastics fit on a 2001 yz250?

No, the plastics from a Yamaha YZ250F will not fit a 2001 YZ250. The YZ250F and YZ250 have different frame designs, mounting points, and body shapes, making their plastics incompatible. If you're looking to replace or modify plastics, it's best to find parts specifically designed for the 2001 YZ250.