Tax lot maps are numerous and large.
All current records are published by the State of Oregon online at OrMap.com
and are available free. Once there, click the 'I accept' (the disclaimer) button at the bottom of the page and you're ready to proceed.
You'll need to know the township, range and section for the tax lot you seek, which are available from the county tax assessor's office
The online tax maps are in .PDF (Adobe Acrobat) format, which means you'll also need a copy of the free Adobe Acrobat Reader
installed on your computer.