Use the Haynes manual from here: http://www.xs400.com/threads/re-run-free-full-yamaha-service-manual.14495/#post-151524
There's also this service manual here: http://www.xs400.com/threads/re-run-free-full-yamaha-service-manual.14495/#post-165053
The bulk of the Haynes manual is about the earlier models but there's a section in the back that details everything different about your bike.
Everything for 1981 models will be applicable to yours. Ditto for buying parts online.
There's also this service manual here: http://www.xs400.com/threads/re-run-free-full-yamaha-service-manual.14495/#post-165053
The bulk of the Haynes manual is about the earlier models but there's a section in the back that details everything different about your bike.
Everything for 1981 models will be applicable to yours. Ditto for buying parts online.