ok to set the choke

with engine cold and the intake hat off, the flap should be closed, look at the little gear type linkage on the side that actuates it and you will see 2 lines, they should line up, if not the tension is wrong, to set that look round the back/side of the carb where the water hoses connect and you will see a screw sticking out of a cylindrical chamber, turn that till they line up, now the amount of choke and time it stays on should be right

next the fast idle speed, have a good look at the throttle linkage and down out of the way youll see a screw you cant get at unless you are holding the throttle full open, thats the fast idle, to set hold the throttle open and screw it in a bit, let it go and start it up and see, I guess you want 1000-1200 rpm.

should be all good then, before doing this when the engine is up to temp check both water hoses into the carb are hot, otherwise there is a blockage and the choke will never turn off