A 55-year-old motorcyclist was killed in a crash with a vehicle in Plainfield on Saturday night, one of eight fatal crashes involving motorcycles in New Jersey over the weekend, authorities said. The motorcyclist was riding east on 7th Street at 7:23 p.m when he collided with an SUV traveling north on Central Avenue, Plainfield police said. The motorcyclist’s identity was not immediately available, though Capt. Christopher Fortunka said the man was from Plainfield. No one in the SUV was injured. The SUV driver has not been charged or issued summonses, though the crash remains under investigati…