Good afternoon and Merry Christmas.
Since the last post the engine has been out, received new crank seals and everything put back together nicely. Crank seals were due to be replaced, but were not cracked or broken and no obvious blow by. Engine still ran the same. I then convinced myself that it must be that the fuel degraded over the summer and it needed fresh fuel. So, the old fuel came out and fresh fuel went in. Still runs the same.
To recap -
Prime the engine and it will start and act like it is running properly for 30 seconds or so and then it dies. Re-prime and it will start again. Alternatively, if I open the enrichener when it starts to die it will come back. It will stay running with the enrichener open.
The carbs have been out, all the jets replaced, and carb cleaner blown through each of the ports.
Still not sure what I am doing wrong. Earlier this year it would start and run just fine. It was only toward the end of summer that it started behaving this way.