Dani Pedrosa, a double race winner during his debut MotoGP season on 990cc machinery in 2006, got his first taste of 2012 1000cc power during Monday's Brno test.
The Repsol Honda rider, forced to miss his planned RC213V debut in May after being injured, rode for 37 laps with a best time 1.096sec behind pace-setting team-mate Casey Stoner.
The test marked Stoner's third day on the RC213V, while Yamaha riders Jorge Lorenzo and Ben Spies were within 0.138sec of the Australian during their debuts on the 2012 M1.
Pedrosa expects the Honda to change a lot between now and its first race - and admitted that he needs to adapt his riding style to get the most out of the more powerful machine.
"My first impression in the morning was that the feelings were quite similar to those I had when I first came into MotoGP, you can feel the difference in torque and power," said Pedrosa, who crashed from the lead of Sunday's Czech Republic Grand Prix.
"Perhaps I was still riding it with a 800cc style and I need a little more understanding again and try to ride it differently, but the bike seems to work quite well.
"We will make many modifications, so the final version will be very different to today's bike, but this is normal and the first impression is quite good.
"Compared to the 990cc I rode in 2006 it's very similar on the power side, but a little lighter in weight and behaviour."
Pedrosa felt that a chassis developed since Stoner's earlier Jerez test was a step forward, but doesn't think any firm conclusions can be reached until the 2012 Bridgestone tyres are finalised.
"I tried one run with the prototype Casey tested in Jerez and also the other one with some modifications and it was a bit better," said Pedrosa.
"We have to be very careful with the chassis because perhaps the tyres next year are a little different in construction which will affect the chassis."