How to tune a streetbike engine for Grands Prix
Mugello, Italy – Triumph has been announced as the engine supplier for the Moto2 world championship from 2019.
The British bikemaker has signed a three-year contract with Dorna, the commercial rights holder of MotoGP, to supply a dedicated, race-tuned 765cc three-cylinder engine, based on the all-new 2017 Street Triple.
The new engine has been developed from the race-winning Daytona 675R that has taken Triumph to Supersport wins at the Isle of Man TT, Daytona 200 and the British Supersport championships in 2014 and 2015.
It’s based on the hottest production version of the 765, the Street Triple RS, further developed for Grand Prix racing to enable it to breathe more freely and rev harder, giving it significantly better performance than the road bike (although neither Dorna nor Triumph is quoting any output figures), while other changes have been made to adapt the engine for racing.
Here’s how it works
The cylinder head has revised inlet and exhaust ports for optimised gas flow, titanium valves and stiffer valve springs for increased rpm.
A low-output race kit alternator reduces crankshaft inertia, while the gearbox has a taller first gear and and an adjustable slipper clutch.
The engine covers on both sides have been revised to reduce the engine’s overall width and, since race engines are always drained with the exhaust system removed, there’s a special sump that allows a better routing for the headers.
And finally, a specific Moto2 ECU has been developed for the contract engines, so that their output will be as close as possible to identical, in the interests of fairness and closer racing.
'Direct and controllable'
Spanish rider Julian Simon, the 2009 125cc world champion, Moto2 runner-up and experienced test rider, has been working with ExternPro, which will be preparing and testing the engines for the race series, on the development of the new Grand Prix engine at Motorland Aragon, a very technical circuit that demands precision engine control.
“The engine feels strong and in particular the mid-range is very impressive,” he commented. “The feel between the throttle and the rear wheel is very direct and controllable; the general feeling is very good and the engine already shows great potential.”