I did. In 40 minutes. Domestic-domestic KLIA2-KLIA.

1) what is the flight arrival time at KLIA and then departure time at KLIA2.
2) With checked in luggage? How long did you have to wait for your checked in luggage to appear? KLIA bags take at least 20 minutes from landing to when the first bags appear on the belt.
3) Which gate were you parked at on arrival (KLIA) and which gate were you parked at for departure (KLIA2)
4) If you had never flown to KLIA before or used the train from KLIA to KLIA2 and then to navigate from the arrival hall and to locate the lift's (good luck trying to get into the lift's with a large volume of bags) going down to the train level and then to go back up at KLIA by lifts and to push your bags up to the Air Asia departure counters to firstly get your boarding pass from the machine if you have not checked in online yet, and then to line up to drop off your bags (I have never had a straight walk through to drop by bags...it was always a 15-30 minute line waiting to drop off my bags).
5) The walk from departure area through immigration, security and to the gates depending on WHICH GATES....

I am saying for a newbie who has never done a trip from KLIA to KLIA 2, it is impossible to do it in 40 minutes from gate to gate.

No checked luggage. I was first guy to get out from AirAsia plane, walking to the train took 15 min (I walk fast), 10 min waiting and ride, 15 min to get out from train and get thru security with already printed boarding pass.

I've been at KLIA/KLIA2 dozen times, so know where to go and how. However do agree that if you have not been there before, it will be a hassle.

It takes you 15 minutes to walk from the aircraft to the train...average people take 20 minutes, not forgetting immigration clearance, waiting for bags....which is impossible to get to KLIA 1 in 40 minutes for the average person.

Using your 40 minute example I think in this case, may be a little flawed my friend

You have not seen how I walk.

I've done an intl-intl T2-T1 connection before, in 40 minutes. If the wait at immigration and the train station are short, it's doable.

Stop dismissing the experiences of others just because you don't think it's possible.

Possible with no checked in baggage. Only hand luggage no need to get out of terminal, just get a transfer.

I'm looking to book SIN-KUL, and KUL-SIN-XXX as two separate tickets, with the SIN/KUL sectors either on SQ/MI. The J fares out of KUL are fantastic! Can do this without a checked bag.

Understand airside in KUL is similar to SIN. To avoid having to go through immigration (and while being on separate tickets), guessing I can do OLCI for KUL-SIN and show a mobile/printed boarding pass once I land in KUL? I recently had a friend doing a similar transit in KUL and was told by SQ staff that he had to exit, go through immigration, and use the regular check-in counters.

Has anyone experienced a smooth transit on SQ on 2 separate tickets at KUL using OLCI? (or other tips?) Thank you!

Flights between SIN & KUL are almost like a shuttle service with high frequency, so why cut it so tight? Can't you take an earlier flight? Even just an hour would buy you quite a bit of margin to cover any potential problems.

Piling onto this thread since it's KL related:
At KLIA & the budget terminal. are they using any automated machines at Immigration or is it all still manual (passport stamped on the way in & out)

They have automated machines for locals and for foreigners who have already previously signed up. Don't worry immigration clearance there is usually quite fast.

Flying out of NRT, arrive KUL 6:10pm on Japan Airlines flight, xfer to domestic Malaysian airlines flight KUL-Kuching at 9:15pm. Assuming 3 hours is more than enough time w/checked bags to clear customs at KUL.

Would appreciate confirmation or thoughts from others who have connected to a domestic flight after arriving internationally. Thank you

More than enough. Is there an earlier KUL-KCH flight? Minimum is 1 hour but 1.5 is better. JL is almost always on time to KUL. Your bags (even if it's on separate tickets) can be checked through to KCH with JL-MH connection. You collect your bags in KCH. However, you'd clear immigration twice, once at KUL to get into the domestic departures and once again when you enter KCH.

If your connection is 3 hours, then I suggest you us the international lounge (if eligible) before proceeding to clear domestic immigration at KUL. The lounge/airside is not the best way to spend most of your layover.

I have a Y-class ticket on Malindo Air, CGK-KUL-PEN, with a 1 hour connection (12:45 - 13:45) in KUL. Will be HBO.

I assume I will have to clear Immigration and then to go to Domestic for the KUL-PEN flight. The last time I had to clear Immigration at KUL it took about an hour, with huge queues, so I imagine my chances of making this connection might not be great.

Any thoughts would be appreciated.