Complex sentence: The 1924 Isle of Man TT was the first race for Ultra-Lighweight motorcycles not exceeding 175 cc engine capacity, won by Jack Porter, on a New Imperial at an average speed of for three laps of the Snaefell mountain course.
Split into simpler sentences: The 1924 Isle of Man TT was the first time the Ultra-Lighweight TT race took place for motor-cycles not exceeding 175 cc engine capacity. It was won by Jack Porter, riding a New Imperial motor-cycle at an average speed of for 3 laps of the Snaefell mountain course.