KT745 ISSUE

I had to replace the head gaskets on my KT745 due to one blowing out.  After putting everything back together it doesn't want to start on choke and when I did get it started it doesn't sound right, kind of muffled sounding and it sounds like it is sucking air around carburetor/air intake.  Looking for advice as to what to look for to get this thing running.  I did pull the carburetor again to make sure the gaskets were reinstalled.  I double checked torque on head bolts after reinstalling and I did check for valve function and clearance.  I am admittedly not a mechanic so looking for advice.