Pressure washer

First, being a "flat head" engine, check and tighten the three HEAD BOLTS closest to the exhaust valve.
 
They OFTEN loosen up just enough so the engine won't run..
 
If that doesn't fix it, spray some carb cleaner down the throat of the carb 
while cranking and see if it licks off momentarily..
 
Advise.
 
.

Ok -165 in/ lbs torque . I will give a try tomorrow- fingers crossed

I have them torqued down ,yes they were loose . I got it to pop  a little ,I am asthmatic so I am only good for about ten pulls and I am done ,then my wife ushers me into the house   . This type of motor I have tuned up for friends and neighbours on lawn mowers for years . Fresh gas ,fresh oil and spark plug and they are good to go . I have never had an issue  . 
I plan to pull the carb apart again and determine if I have missed something .
 The head torque was a excellent tip - Thanks Scott