A motorcyclist was killed in a single-vehicle accident on Highway 142 in Klickitat County on Monday.  The Washington State Patrol says the motorcycle driven by 25-year-old Austin Whittington of Portland was eastbound on Highway 142 at milepost 22 at about 1 p.m. on Monday afternoon.  A WSP report says the motorcycle failed to negotiate a curve and continued straight off the roadway over a steep embankment.  The motorcycle struck multiple trees before coming to rest 30 feet down the embankment.  Whittington was declared deceased at the scene.  The WSP cited excessive speed as a cause of the crash.