Seon,
I'm thinking along the same lines as Mozzie. You indicate you timed it 4° BTDC, and I wonder how you came to that value. Do you have a advance timing light or did you read some little numbers off a plate near the distributor.
The carburetor has a powervalve in it that gives the engine extra fuel when you mash the gas. Although pretty simple to overhaul, if one little ball isn't where it belongs, or a spring is hanging up, things won't work right.
The carburetor to manifold gasket is directional. It must have the slot positioned under a vacuum sensing hole in the carburetor base. Look around a bit more and give us some good news.
Stuart
