Nakagami will continue on a year-old Honda RC213V for his second campaign in MotoGP, sticking with the LCR team.

With Crutchlow still out injured after his season-ending Phillip Island crash, and Honda tester Stefan Bradl sitting out the Jerez test, Nakagami has been LCR's only representative for the final running of 2018.

The Japanese rider impressed on Wednesday, setting the third-fastest time - behind only factory Ducati pair Danilo Petrucci and Andrea Dovizioso.

After spending a year on the notoriously tough-to-ride 2017-spec Honda, Nakagami said the the difference with the 2018 version was immediately noticeable when he first tried it in Valencia.

He said the power delivery was "sweeter" and allowed him to lap much more consistently than previously.

"I'm just enjoying the '18 bike, which Cal has been using this year," commented Nakagami. "The engine is a really big improvement compared to 2017.

"It’s easy to ride because the engine has a lot of power, but the bottom [of the rev range] is much easier to ride, the laptime is much more consistent and if I push the laptime it's easy to improve.

"When I jumped on the '18 bike, from the middle to the top it’s improving a lot, [its] easy to feel.

"In Valencia we were not 100 percent fixed on the electronics side, [there's a] different delivery of power, and we have to do an adjustment from the bottom to the middle.

"On the '18 bike it’s a little bit difficult to feel the spinning, because the feeling is very sweet on the bottom, [you are] able to open [the throttle]. But you increase the power and it’s easy to spin [the rear wheel].

"Here in Jerez, first day, I feel quite competitive with the laptime, the position. But [there are] small things we need to improve."

Asked if his speed came as a surprise, Nakagami adopted a cautious tone, saying: "Not surprised, [but] still this is a winter test and I think everybody is not really pushing like on a race weekend.

"Even for me, I’m not pushing like a race weekend. Difficult to understand, because some riders test [with] new tyres [and others don't]. Difficult situation, [you] cannot understand."

Nakagami is working with a new crew chief this year, with Giacomo Guidotti moving over to LCR after a spell as Dani Pedrosa's chief mechanic.

Guidotti replaces Ramon Aurin, who has moved in the opposite direction to work with Jorge Lorenzo at Repsol Honda.

"Step-by-step we understand each other and try to make more communication to get the information," said Nakagami of his new crew chief.

"I try to give my riding style to Giacomo, and Giacomo tries to understand my riding style. Step-by-step we are improving communication."