Ben Spies led an all-Yamaha top four at the head of the Sepang timesheets on day two of the second MotoGP test of the season, which saw just two hours of dry running and no Hondas.
Factory Repsol Honda riders Casey Stoner and Dani Pedrosa had been first and second on day one, interrupted by a brief afternoon thunderstorm.
However the cause of a late engine problem for Pedrosa - which he was alerted to by a red warning light on his final run, then shut down his machine - was still being investigated on Wednesday morning.
As a result all four RCVs - the Repsol bikes plus Alvaro Bautista's Gresini machine and Stefan Bradl's LCR - were absent when the track opened under cloudy skies at 10am and wouldn't be seen for the remainder of the day.
The Honda race teams received the all-clear from Japan shortly after lunch, but the wet track and limited time remaining meant they elected to return on Thursday.
By the time the rain arrived at midday, Spies - fourth on day one - was leading by just 0.008sec from team-mate Jorge Lorenzo courtesy of a 2m 1.285s best. That is half-a-second inside Stoner's Tuesday time, but some way off the 1m 59.607s set by the Australian at the first test earlier this month.
Without the Hondas, the reduced 11-rider Wednesday timesheet saw the four Yamahas being followed by three Ducati race riders - Cardion AB's Karel Abraham has withdrawn from the test due to his Jerez injuries - then Ducati test rider Franco Battani and finally the three CRT machines.
Behind the factory M1 riders were satellite Tech 3 duo Andrea Dovizioso (+0.237s) and Cal Crutchlow (+0.410s), with Nicky Hayden once again the top Ducati, in fifth.
The American, relieved to be able to ride properly this week after recent shoulder surgery, lapped 0.463sec from fellow American Spies, with Pramac Ducati rider Hector Barbera (0.704s) and Hayden's factory team-mate Valentino Rossi (+0.845s) completing the top seven.