The good old "go you stink rotten muddr fu" Be care ful with aurostart, went to a maching thet had a couple of tins sprayed into it once (wont start because the crowd lever was engaged and was lifting the relief valve) it knocked for 20 minutes after I got it going, operator said he didnt spray areostart until I pointed out the 2 empty tins sitting beside the air cleaner.
This is the engine you done up, isnt it ?
I wonder wether it has a crook top or bottom crank seal and sucking air, maybe starting at home because of the less back pressure, possible still have less back pressure in a drum that in the water proper.
cheers
blaze