Flight Changi Airport departs from Singapore Changi Airport at 16:05 and arrives at Hong Kong Hong Kong International Airport at 20:20.
The flighttime is about 4h 15m. The distance travelled ("as the bird flies"): 1322 Km. So the average speed is roughly 311 Km.
The best day to arrive at Singapore is Tuesday and it would be best to avoid Saturday, as prices are on average 57.43% higher than on Tuesday. (Average prices, based on 2226944 datapoints.)
We have a lot more statistics for flights CX 734 and between Singapore and Hong Kong.