A large part of the Rotax's efficiency is the gearbox. The engine runs at a more efficient 5,500-5,800ish rpm(similar to auto engines). That and the higher compression ratios allowed because of the water cooled cylinder heads. One particular feature about Rotax is, no traditional mags. Magnets are cast into the crankshaft and these brush against coils (similar to a dynamo). The ignition units themselves are sealed boxes and you don't have to worry about inspecting them.