Repsol Honda's Dani Pedrosa was immediately on the pace at Sepang in Malaysia on the new RC213V.
The Spaniard clocked the second quickest time behind Yamaha's Jorge Lorenzo, completing 48 laps on the 1000cc machine, which was similar to the bike he tested at Valencia in November.
With Pedrosa's team-mate and reigning world champion Casey Stoner sitting out the first day of the test after pulling his back while he was warming up in preparation for the shakedown, Pedrosa and HRC test rider Kosuke Akiyoshi gained valuable track time on the new RC213V.
Pedrosa, whose fastest lap of 2m02.003s gave him the second top time behind Lorenzo (2m01.657s), said: “Today was good, for the first laps I think it was important for me to come back and just ride again.
“Of course, the first day I was a little bit stiff, not totally smooth on the bike, but we completed some laps and they were good.
“Today was mainly a test for myself, to get used to the bike again, recover the feeling, feel the throttle and the brakes after a long time off.
"The whole day I stayed with the same bike that I tested in Valencia in November and tomorrow the real test will start for us, we will work on the set up and probably try a modified chassis that Honda has brought here according to our requests after Valencia.”
Stoner has received treatment from a physiotherapist and hopes to be able to commence testing tomorrow.