Jorge Lorenzo made his first appearance on the Honda since breaking his left wrist during training in January in Saturday's Qatar pre-season test, and was 21st overall.
Lorenzo missed the first test of the year in Malaysia two weeks ago after fracturing his scaphoid during a dirt bike training accident last month. He was replaced by HRC test rider Stefan Bradl at Sepang.
The triple MotoGP world champion completed 38 laps on his first appearance on the RC213V since November on Saturday, and was 2.039 seconds off the pace in 21st.
Commenting on his first day on the bike since injuring his wrist, Lorenzo said: “Well, the wrist obviously on braking I struggle.
“But at least I'm able to do runs of two or three laps to understand the bike and to understand everything.
“The problem is we don't have so much time, maybe three hours every day because after nine o'clock the conditions start to drop a lot in temperature.
“So, it's difficult to take profit like in another track when you have all day, many laps. We didn't try so many things, we didn't try any set-up, we didn't try anything to improve the bike.”
Admitting he needs “more time on the bike” to fully understand it, Lorenzo has highlighted the ergonomics – which proved to be an issue in his first year on the Ducati in 2017 – as the key area to improve.
“We still have long way, for me, to find the best ergonomics, because on the foot pegs I slide, I don't have enough support on acceleration on the seat,” he added.
“So still need to modify it and to change many things on the ergonomics. And physically I have the wrist with the injury, and I need much more time on the bike because four months [without riding] is a lot.
“Even if you train very well in the gym, when you arrive to the bike you use different muscles and I need more bike to be fitter.”
He noted the engine has improved since he last rode the bike at Jerez last year, noting team-mate Marc Marquez setting the best speed trap figure at 348km/h on Saturday, though feels he is “losing a little” with the aerodynamic set-up at present.
“I think we improve the engine, the engine is quite fast. Marc today was the fastest one on the straight, which is a good sign because Honda last year probably lose so much speed compared to the Ducati.
“348km/h [on the straight], the fastest one, is a good thing. We still need to improve the aerodynamic because I'm losing a little bit compared to Marc and [Cal] Crutchlow.
“But we are too far to make so many conclusions. Tomorrow we will be closer and we will improve all the small details.”
