Hello
the ignition timing is preset via the crankshaft sensor but check for vacuum in small bore pipes from carb base , its more likely to be a fuel problem, pumping the accelerator also does nothing on the 126 as there is no accelerator pump on this type of carb, however there are a few things to check , mine is also difficult to start from cold and seems to prefer half choke on cranking from cold , also mixture setting , this is trial and error if you dont have an emissions tester basically turn mixture screw in clockwise direction counting number of turns until it stops , then unscrew by one full turn , although this method might take a while as youll need to check starting from cold again after a few hours and maybe unscrew a further half turn each time, im thinking that the electromagnetic solenoid(on carb) is working ok as tick over is fine once running