Okay I'm left with these ideas:

- swap fuel line from 1 to 2
- float is out
- jets/emulsion tubes are way off

It ran very well for 20 mins while we warmed it up, not just idle but once I got the idle mixture set (responded to setting very well) it picked up revs nicely. Even our first lap around the block was really good, picked up revs nicely. Second lap it started chugging in 3rd and stalled when I pulled over.

Now it doesn't run >20 seconds at all - not matter what...

Also the auto choke never actually chokes, even with the coolant running into it, haven't worked that one out yet...