1988 Yamaha YZ250 Service and Repair Manual

Model code YZ250U is the 1988 YZ250. Yamaha's service manual for it carries part number LIT-11626-06-21 and addresses that season on its own.

Manuals from the late eighties sit between the terse early books and the heavily illustrated modern ones. They give the procedures in order, the specification tables in full, and enough illustration to settle how a part is oriented. Engine internals, clutch and transmission, chassis and suspension, fuel and ignition systems, and the electrical harness are all covered, with the wiring drawn out.

The inspection material is the part to read before ordering parts rather than after. It names what to measure and gives the limit, which often shows that a component you assumed was finished is still inside tolerance, or the reverse. Check YZ250U on the frame label before buying.