Valentino Rossi says the engine modifications Ducati trialled at a recent Mugello test have not worked, and that the team needs something "more radical."
Ducati had pinpointed corner exits as one key area it was losing out, with both Rossi and Nicky Hayden struggling to apply the power without breaking traction.
As a short-term fix Ducati tested modified engine settings at Mugello last week with a view to bringing them in at Silverstone. That now looks unlikely, with Rossi saying the changes had not proved beneficial. He says extra focus must now be devoted to designing and testing the longer-term, more thorough update aimed at being brought in for the U.S. Grand Prix at Mazda Raceway Laguna Seca.
"There are no improvements, I knew it before testing it," Rossi told Gazzetta dello Sport. "We need something more radical and they're working on it.
"Our program schedules to have it for Laguna Seca, but this means that we'll first do more testing at Mugello, because we can't think of taking it to the races without knowing how it goes."
Despite the setback, Rossi said his goals at Barcelona – to close the gap to the Tech 3 Yamahas – had not changed.
"Now we'll have to see what happens here," he explained, "if we manage to close the gap to the ones ahead of us in the dry, like the black Yamahas and Barbera. Not so much in practice, but on Sunday afternoon."
Hayden echoed Rossi's thoughts on the engine tweaks, adding that in some ways it was actually a step backward.
"At low regimes it hasn't improved, while at high regimes it has lost something," Hayden said.