The 20-year-old first rode a YZR-M1 during a secret test at Almeria during the
MotoGP summer break, but Valencia marked his first time working with the factory Yamaha team - which will be restructured next season to allow
Valentino Rossi to race with
Bridgestone tyres, while Lorenzo uses Michelin tyres.
Rossi has returned home for further treatment on his right hand, which he broke during qualifying on Saturday, but Lorenzo completed 52 laps throughout the afternoon and finished a creditable tenth with a best lap of 1min 34.320secs, just under two seconds from Ducati's world champion
Casey Stoner.
"I'm very proud to be here in this garage and it's been quite an emotional day for me!" confessed Jorge. "I'm very happy to have the chance to try my new bike and I enjoyed myself a lot today. My first aim has just been to get comfortable on the bike and to try to understand as much as I can about it. I went very gently because the difference in power from my 250 bike is very big! I am definitely a long way from the limit but I think I made a good start. We need a lot of time and a lot of kilometres in order to learn about the bike, but I am looking forward to improving at each test."
"This afternoon the aim was to get Jorge comfortable on the bike - this is the most important thing at this stage," confirmed Lorenzo's team manager Daniele Romagnoli. "We adapted the handlebars and ride height to suit him and changed around a few other things to get him into the right position. We also worked a bit on the engine braking system because for him this is one of the biggest changes between a two-stroke bike, which is what he is used to, and a four-stroke MotoGP bike. He put in a lot of laps and it's been an interesting and exciting day for everyone. We're looking forward to having another whole day tomorrow."
