Petter as engine

Hi there. I am new to stationary engines but have gained a petter as petrol single cylinder engine. Looking on google there is very little info about it. The engine does run run when it wants to but is a absolute pain to get going. I have cleaned fuel tank, fuel bowl, blown through the fuel pipe and cleaned the carb. I have a good spark so guessing the next step is the timing. Would anyone have any idea how to set the timing correctly on a AS (is it the same as a A1). Any help or info would be great to help a novice out here. Many thanks