MotoGP world champion Jorge Lorenzo rode some laps on the Yamaha test team M1, as well as his usual factory race bike, during day two of this week's Sepang MotoGP test.
The purpose of the switch was to make sure that new parts offer an advantage and, for the new chassis at least, the outcome was clear.
“We tried the test bike. It was last year's chassis fitted with the new engine and forks. We reconfirmed that the new chassis is better,” said Lorenzo, who finished the day fifth fastest, 0.76sec behind Honda's Casey Stoner, and also set the ninth fastest time with the 'T2' bike.
“The condition of the track has changed a lot from two weeks' ago [at the first test] so it is important to try the old parts to be sure. Also when you go to a new track, it is a completely different story.
“We also tried last year's forks and suspension today [although] we still don't know which is better. But the chassis, yes, the new one is definitely better here.
“We have more grip on the rear tyre with the new chassis, which gives better corner-entry confidence and more traction on the exit.
“But we need more power. This is where Yamaha have to work. It is going to be difficult [to get more power in time] for the first races. Maybe later.”
Lorenzo's team-mate Ben Spies was just ahead of him on the end-of-day timesheets, which was led by the three Repsol Hondas.