TOKYO, Nov 7 - Japan's core machinery orders likely rose in September from August helped by buoyant exports, a poll by journalists showed on Friday. The poll of 28 economists produced a median forecast for a 5.1 percent rise in September core orders. Forecasts ranged from a fall of 1.5 percent on month to a rise of 12.3 percent. Compared with September last year, orders were seen up a median 7.7 percent. "A rise in exports to Asia and bigger capital spending in the manufacturing sector should help machinery orders reverse contractions in July and August and resume an upward trend," said Hideki Matsumura, an analyst at Japan Research Institute, who forecast a 3.4 percent month-on-month rise in core orders.//