Join Date: Jul 2007
Location: San Francisco/Sydney
Programs: UA 1K/MM, Hilton Diamond, Marriott Something, IHG Gold, Hertz PC, Avis PC
Posts: 8,156
Plenty of time - presuming an on-time arrival.
EVA come into International G, which at that time of day has a few flights landing but not a huge number. Absolute worst case you should be through both immigration and customs within an hour. If your luggage was tagged all the way through to PDX then you'll still need to collect it at SFO and drop it back on the belt. If it wasn't, it's a short walk to the UA check-in areas.
Then back through security and to your gate. Easy to do in less than 2 hours.
If your inbound is late then obviously it could be a different story, but FlightAware claims it's average delay is less than 10 minutes - and United are pretty good at rebooking you on a later flight if you arrive late, even on a separate ticket (the good old "flat tire" rule).