Agree with Backfoot, also concerned with the fuel filter used. Is the carb running out of fuel, or flooding? When giving issues & you look down the throat of the carb is fuel dribbling in?? OR when is quits & you look down the throat & pump the throttle is fuel squirting or is it dry?? Before going further we need to know if its flooding or starving. The angle is not the issue, this can be dealt with via float level like Backfoot said.