Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 08:30 and arrives at Kuala Lumpur Kuala Lumpur International Airport at 11:50.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 600 Km. So the average speed is roughly 257 Km.
There is an 1 hour time difference between Jakarta and Kuala Lumpur