Self transfer time at bkk

Is 3 hour 45 mins enough time for a self transfer at bkk? Incoming international flight at 6am and separate ticketed Bangkok air flight to Samui at 9.45am. 

Would have to go through immigration and collect checked luggage then re enter the departure terminal and check in, drop baggage 
 security etc 

Anyone done it recently with that sort of time. Next available flight to Samui would be an hour and 45 mins later which would take the transit time up to 5 hours 30. Is that better? 

Thanks in advance