2001 Yamaha TTR225 Service and Repair Manual
Stamped TTR225N, the 2001 TTR225 is served by Yamaha service manual LIT-11616-TT-26. The book's coverage takes in 1999, 2000, 2001, 2002 and 2004, together with the TT-R225 and TTR225L.
A used trail bike of this generation has usually been apart at least once. What the factory document provides is the baseline: the clearances Yamaha specified, the order in which the engine goes back together, the carburettor settings it left the line with, and the wiring as originally drawn.
Troubleshooting sections start from what the bike is doing wrong and work back to the cause, which is how most jobs begin in practice.
Two checks before ordering: LIT-11616-TT-26 as the part number, TTR225N as the code on your machine.
Nothing in it has been condensed for a general audience.