Following Sunday's Valencia MotoGP season finale, an official test session is being held at the circuit from Monday to Wednesday.
The test marks the first appearance for Cal Crutchlow at Ducati, Moto2 world champion Pol Espargaro at Yamaha Tech 3 and former title rival Scott Redding at Honda Gresini.
Redding plus Aspar's Hiroshi Aoyama and Nicky Hayden are testing the new Open class Honda Production Racer, with Hayden - who sat out Monday due to limited machine numbers - getting his first ride on the RCV1000R today.
The new privateer Forward Racing Yamaha is making its public debut on Tuesday in the hands of Aleix Espargaro and Colin Edwards. New world champion Marc Marquez and Repsol Honda team-mate Dani Pedrosa are also back on track after skipping day one.
Marquez is already comfortably under the new official race lap record. The 20-year-old - riding with a special helmet design - saved the 2014 Honda with his knee and elbow after a big lowside moment at turn six, shortly after 1pm.
Valentino Rossi is working with his new crew chief Silvano Galbusera for the first time, while former Aprilia Racing boss Gigi Dall'Igna is present in his new role as general manager of Ducati Corse.
The 2014 rules will see the Factory class bikes lose a further litre of race fuel relative to the Open class machines, raising the difference to four litres. The Open bikes must run the full control ECU system, while the Factory entries can use their own software.
Tuesday's track action began at 10am and concludes at 5pm.
for more pictures from the test...
1. Marc Marquez
ESP Repsol Honda Team (RC213V) 1m 30.679s
2. Jorge Lorenzo
ESP Yamaha Factory Racing (YZR-M1) 1m 30.935s
3. Dani Pedrosa
ESP Repsol Honda Team (RC213V) 1m 31.031s
4. Alvaro Bautista
ESP Go&Fun Honda Gresini (RC213V) 1m 31.208s
5. Stefan Bradl
GER LCR Honda MotoGP (RC213V) 1m 31.239s
6. Valentino Rossi
ITA Yamaha Factory Racing (YZR-M1) 1m 31.646s
7. Bradley Smith
GBR Monster Yamaha Tech 3 (YZR-M1) 1m 31.793s
8. Andrea Iannone
ITA Energy T.I. Pramac Racing (GP13) 1m 31.980s
9. Pol Espargaro
ESP Monster Yamaha Tech 3 (YZR-M1) 1m 32.093s
10. Andrea Dovizioso
ITA Ducati Team (GP13) 1m 32.556s
11. Nicky Hayden
USA Power Electronics Aspar (RCV1000R) 1m 32.582s
12. Cal Crutchlow
GBR Ducati Team (GP13) 1m 32.605s
13. Yonny Hernandez
COL Ignite Pramac Racing (GP13) 1m 32.800s
14. Aleix Espargaro
ESP NGM Forward Racing (FTR-M1) 1m 32.847s
15. Michele Pirro
ITA Ducati Test Team (GP13) 1m 32.937s
16. Randy de Puniet
FRA Paul Bird Motorsport (ART) 1m 33.833s
17. Michael Laverty
GBR Paul Bird Motorsport (PBM-ART) 1m 33.843s
18. Colin Edwards
USA NGM Forward Racing (FTR-M1) 1m 34.123s
19. Scott Redding
GBR Go&Fun Honda Gresini (RCV1000R) 1m 34.580s
20. Mike di Meglio
FRA Avintia Racing (FTR-Kawasaki) 1m 34.618s
Fastest day one time:
ESP Yamaha 1m 31.257s
Official Valencia MotoGP records:
ESP Honda 1m 30.237s
Fastest race lap:
ESP Honda1m 31.628s
Fastest 2013 race laps by manufacturer:
ESP Honda 1m 31.628s
ESP Yamaha 1m 31.701s
USA Ducati 1m 32.764s
ESP ART 1m 33.323s
ESP FTR-Kawasaki 1m 33.551s
ITA Suter-BMW 1m 34.153s
AUS FTR-Honda 1m 34.815s
GBR PBM-ART 1m 35.886s