Riyadh is 11 hours ahead of Portland
There is no standard 8-to-6 overlap. Someone joins early or late.
An 11-hour difference puts Portland and Riyadh out of sync — when one team is mid-morning, the other is fast asleep. Consider rotating the inconvenience: one week Portland takes the early call, the next week Riyadh does. These times hold for most of the year, but Portland's daylight saving (which Riyadh doesn't use) shifts them by an hour twice annually.