Repsol Honda riders Marc Marquez and Dani Pedrosa will have two different engine specifications to try during this week's Sepang MotoGP test.
The pair will test the 2016 engine used at last November's Jerez test, plus a new 'evolution' spec.
After last season's difficulties Honda is focusing on fixing the RC213V engine character in time for round one in Qatar, after which no further engine design changes are allowed.
But the task of taming the engine has been complicated by adapting to the new single ECU software and the debut of a new spec for Sepang indicates that HRC are not convinced that the Jerez engine is the solution they are seeking.
“Here both riders have two bikes equipped with two different engine specs, the one they already tried at Jerez in November and an evolution. We'll carry out a comparison between the two and of course we'll work also on chassis, electronics and tyres," said HRC technical director Takeo Yokoyama.
“We hope that after three days we'll be able to see the direction of the bike development, which will help us in the tests at Phillip Island and Qatar.
“For the last two days [at Sepang], we've been testing with our test riders Aoyama and Takahashi. The track conditions are far from perfect, but even so we've found some good directions.
“The things that worked will be given to our official riders, Marc and Dani, and we hope that they too will find that we've gone in a good direction”.
Last year's two Sepang tests lulled Honda into a false sense of security over its 2015 engine - the searing heat dulling the engine character and suggesting a fix had been found. When the aggression duly returned in the final Qatar test it was too late to solve for the start of the season.
This year there is only one test at Sepang, with Phillip Island added before Qatar.
While Repsol Honda works on the 2016 engine this week, satellite riders will test with the 2015 specification.