The secrets of the new Yamaha Tracer 9 engine

The Yamaha Tracer 9 2021, like its predecessors, it is equipped with a forward-facing three-cylinder engine. It is a new unit, shared with the MT-09 2021, similar in some features to the one it replaces. We are referring, for example, to the chain-driven double overhead camshaft timing system with thin shoe tensioner; to the four valves per cylinder; to forged pistons combined with connecting rods with separation between cap and half-head obtained by fracture; at the compression ratio of 11.5: 1; to the crankshaft with crank pins offset by 120 ° (the order of the bursts is therefore regular, every 240 ° of rotation of the shaft), combined with a countershaft to dampen vibrations; to direct facing cylinders mounted at an offset (forward) from the crankshaft.

Macroscopic differences with the unit previously used on the Tracer 900 they affect everything else, starting with the intake system. The three ducts each have a dedicated length and shape, in favor of both delivery and sound: the House’s Music division contributed to the development of the intake and exhaust systems to ensure that the “voice” of the engine was the most beautiful as possible. The throttle bodies are now full ride by wire and have injectors in the traditional position (on the old engine they were housed directly in the head). According to the manufacturer, this change significantly improves engine efficiency, reducing consumption by 9% (WMTC cycle). Then there are new bore and stroke sizes, which go from 78 x 59.1 mm to 78 x 62.1 mm. The displacement increases accordingly from 847 cc to 890 cc. The crankshaft has a 15% higher inertial mass, and the gearbox has first and second “longer”: the ratios go from 2,667 (40/15) in first and 2 (38/19) in second to 2,571 (36 / 14) in first and 1,947 (37/19) in second. The selector forks have been redesigned and the clutch, with multiple discs, in oil bath, with slipper, is new. The ratios of the primary (1.681) and final (2.813) transmission do not change.

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Compared to the past, education (Euro 5) and performance improve: the maximum power measured at the wheel goes from 104.5 HP at 10,100 rpm to 108.6 HP at 10,000 rpm; maximum torque from 80.9 Nm at 8,200 rpm to 85.7 Nm at 7,000 rpm.


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