Ex-Rangers ace Boyd opened the scoring in just the third minute when he skimmed home Khalif Alhassan's rightwing cross from the front post before Beckham produced a brilliant curling finish from 35 yards in the 19th minute.
Just under five minutes later, Beckham made it 2-1 for the Galaxy with a sublime free-kick that whipped up over the wall and came down inside Troy Perkins' near post prior to Donovan coolly converting from the spot to give his side a two-goal buffer.
Before the half-hour mark, LA had a fourth when Keane slotted home Donovan's cross from close range and then Kosuke Kimura scored a sixth of the half when he followed up Boyd's free-kick which was spilled by Josh Saunders.
Keane grabbed his second in the 64th minute with a deft finish from Sean Franklin's low pass from the right before Boyd completed his brace with twenty minutes remaining courtesy of another free-kick which took a deflection on the way through.
The win allowed the Galaxy to stay fifth on the Western Conference table as the Timbers, after having sacked head coach John Spencer, fell to the bottom with a third loss in four outings.