Czech Grand Prix winner Casey Stoner continued to show his strong form in the post-race test on Monday, when the new-for-2012 bikes returned to action.
The Australian, who extended his lead in the standings with a commanding win on Sunday, posted the quickest time of the day with a lap of 1m56.168s on the new 1000cc machine.
"Today was another good shakedown but we still have some work to do, we found a few positive things and confirmed certain directions to take and move forward," said Stoner. "We had a few small problems with chatter but it's something that shouldn't be too difficult to sort out through engine braking and engine management systems, which are areas we can definitely improve in, along with the chassis.
"The engine for me is fantastic, to ride the 1000 with more grunt and more power it's a lot of fun, it has incredible acceleration, most of the time too much!"
He was followed by Jorge Lorenzo on the Yamaha, the Spaniard riding both this year's and next year's bikes, setting the quickest time with the 2012 prototype machine.
"Today has been an exciting and busy day because it has been the first day riding the 1000cc bike, but also because we have made a small step with the engine upgrades for the 800cc bike," said Lorenzo. "We rode many laps non-stop from nine this morning to five this afternoon!
"I realized the 1000cc bike was incredible when I saw the power on the straight. I like this bike a lot and I wanted to have more laps but I have to still think about this season! I have been just one hour with our future bike! I can say that the next MotoGP season will be amazing, much more power, you go out of the corners sliding; I can't wait!"
Teammate Ben Spies was third quickest, also using the 2012 bike, with Dani Pedrosa finishing down in fourth position, a second off Stoner's pace with the prototype 1000cc Honda.
"The 800cc upgrades we tested this morning were positive, hopefully there's more in that direction in the future as well," said Spies. "With the 1000cc bike it was a pretty successful first day. We didn't change much on it, pretty much just rolled out and did some laps to get as much data as possible.
"We made some small changes to see how differently it affected the bike compared to the 800.There's more improvements to be made for sure but for the first day to go faster than the 800 was a surprise.
"My arm is feeling better and better, I'm getting a check up when I fly home to the U.S. on Wednesday but should be fit and ready for Indianapolis."
The only other rider testing a 1000cc bike was Mika Kallio, slowest today.
Nicky Hayden completed the top five for Ducati, with teammate Valentino Rossi down in eighth.
Pos Rider Team Time Laps
1. Casey Stoner Repsol Honda Team 1m56.168s 57 *
2. Jorge Lorenzo Yamaha Factory Racing 1m56.253s + 0.085 28 *
3. Ben Spies Yamaha Factory Racing 1m56.306s + 0.138 24 *
4. Dani Pedrosa Repsol Honda Team 1m57.264s + 1.096 37 *
5. Nicky Hayden Ducati Team 1m57.533s + 1.365 78
6. Cal Crutchlow Monster Yamaha Tech 3 1m57.591s + 1.423 74
7. Toni Elias LCR Honda MotoGP 1m57.903s + 1.735 56
8. Valentino Rossi Ducati Team 1m58.266s + 2.098 74
9. Loris Capirossi Pramac Racing Team 1m58.387s + 2.219 66
10. Colin Edwards Monster Yamaha Tech 3 1m58.492s + 2.324 44
11. Mika Kallio Marc Vds Racing Team 2m00.144s + 3.976 81 *
* 1000cc bike