MotoGP rookie Jack Miller likened finding the limits of his new MotoGP machine to having 'sex with your pants on' after slicing 0.9 seconds off his personal best lap time on the final day of testing at Valencia.

Coming off a mammoth afternoon session on Monday, which saw the Australian post over 70 laps, he put in a further 60 on Wednesday to end the day 21st overall. Miller's best time was 0.2 seconds behind former World Superbike riders and fellow rookies Eugene Laverty and Loris Baz.

"I'm touching my elbow [on the ground] more than I ever did in my life, through places that I wouldn't expect," said Miller, who has jumped straight to MotoGP after finishing title runner-up in the Moto3 class.

"Through turn three - I'd like to see some photos through there because I was getting the elbow down, then when you get on the gas the thing goes sideways before the braking point before turn four. It's one of the most exciting experiences you know. It's like having sex, with your pants on!"

The 19-year-old again spent the day riding without electronic aides as the LCR team attempted to get him used to the extra power at his disposal. Miller also continued with Honda's soon-to-be-replaced RCV1000R 'Open' racer, which was some 20kph down on the fastest speed trap times.

"We were testing out the couch in the motorhome [due to the rain on Tuesday]! But really good today, it was productive, and we improved a lot more. Every time we're becoming more comfortable with the bike and starting to use the rear tyre to turn, which is becoming more fun for me as a rider. It's an incredible feeling when you come through turn 13 with the handlebars on the stops. I'm really enjoying it. It's a dream.

"Really I'm not so far away. I'm doing better than I expected so this is a bonus. We haven't touched the traction control since I hopped on the bike nor the wheelie control. I was asking Honda to put the wheelie control on but they said, 'No, you've got to keep learning son. You've got a long way to go before you're allowed any of the help-outs.'

"We're learning and coming stronger. Just working out how to get the bike to come out of the corner with the low centre of gravity to stop the thing wheelying too much, even with the power we've got there. We're quite down on power - Marc was doing something like 330kph through the speed trap and I'm sure I didn't go over 310."

Most of the Australian's laps were completed on his own as he got to grips with Bridgestone's harder front tyre, with which he had been struggling on Monday.

"I was struggling [with it] on Monday and it got a lot better today with the harder option, it allowed me to ride without problems. Just working this trail braking out on full angle, it's another world. We really have to find out the limits of the bike.

"I got stuck in behind Marc [Marquez] for two corners today. To watch him and the pressure he puts on the front tyre into the corner gives you a rough idea what this tyre can withstand.

"We know what we've got to do. We were 0.3secs off Laverty and Baz who've come across from Superbikes. They've been riding 160 kilo bikes all year. We're not too far away from the guys that were on this bike. There's a big smile on our face today. We haven't thrown the bike down the road yet."

As a contracted HRC rider Miller now travels to Malaysia for a private test at Sepang, which will allow him to develop on the bike further and get used to the electronics.

"We're getting to the point where we need to start using them but we're learning step by step. We've got a long test period and I'm very fortunate that Honda hasn't put any pressure on us. They really want us to learn so a big thank you to them for the big opportunity they've given me this year. I'll try to train hard before Sepang and try to get in as good a condition as possible."

Miller also confirmed that he is due to have an operation to remove screws from his shoulder over the winter break.