Yamaha debuted the 2023 version of its YZR-M1 engine at the official two-day MotoGP test on Italy’s Misano circuit that followed the Grand Prix there in early September.

Fabio Quartararo used the 2021 version of the YZR-M1 to claim that year’s riders’ world title - the first such title for Yamaha since 2015. At the time of writing after 16 of 20 events Quartararo headed the 2022 leaderboard but he was known to be unhappy with the power output of the 2022 version of the YZR-M1.

The YZR M1 is an I4, by regulation naturally aspirated and under 1000 cc. The mandatory bore of 81 mm is combined with a stroke of 48.5 mm for 999.7 cc. A 10 bar limit on fuel pressure removes the scope for direct injection. Where Yamaha once championed five valves per cylinder, for a long time the YZR-M1 has had 16 valves and those are operated by gear driven double overhead camshafts.

The YZR-M1 has been developed around use of a counter-rotating, 90 degree phased cross-plane crankshaft. In theory a 180 degree phased flat-plane crankshaft can offer more top end power but at the cost of ride-ability. Yamaha hasn’t yet revealed the solution used for its 2023 engine, which like its predecessor runs to a speed in excess of 18,000 rpm.

This engine is the first to break cover since former Ferrari and Toyota Formula One engine chief Luca Marmorini joined the Yamaha MotoGP effort as a consultant. Marmorini was present at the Misano test, from which the news was that Quartararo was very happy with the prototype 2023 engine. He found that it had reduced the top end power deficit to the rival Ducati V4 without compromising what he described as the YZR-M1’s “nice and mellow behaviour” at low speed, nor the balance and cornering speed that is the Yamaha bike’s strength.

Further development steps will be evaluated before the specification of the engine has to be frozen ahead of the first 2023 Grand Prix, at Portimao in Portugal on March 26. Meanwhile rumour has it that in the background Yamaha is toying with a V4 MotoGP bike.