SHEBOYGAN, Wis. — The Americans were looking for a fresh start in the Ryder Cup with its youngest team ever, and it worked out even better Friday than they imagined at windswept Whistling Straits. Dustin Johnson and Xander Schauffele each won two matches and all six U.S. rookies contributed at least a half-point on a day of chill and warmth, sunshine and rain, and a constant dose of American red scores on the boards. The Americans won both sessions to build a 6-2 lead, sending Europe and its vast experience to its largest deficit after the opening day. “I thought 3-1 and 3-1 in the two sessions, that’s a great start,” Patrick Cantlay after his solid Ryder Cup debut.