To determine the correct main nozzle, it is first of all chosen from the gut so large that the target should be an engine that stutters heavily under full load. Of course it needs some experience, but a nozzle can be changed quickly. Once you have found such a nozzle you mount a smaller one until the engine does not stutter under full load anymore. So you have already an ideal basic fuel supply which ensures that the engine does not get too little fuel under full load, which it needs to cool the piston and cylinder. A safety optimum is an engine adjusted in such a way, which throttles down very slightly when you close the throttle under full load.
Gurtner, a French carburettor manufacturer with a tradition of over 100 years, is very popular with French scooter manufacturers as original equipment. Almost all 50cc Peugeot automatic scooters are equipped with the proven Gurtner carburetors. Tip: The Peugeot vehicles are often very leanly tuned, enlarging the main jet allows the vehicles to accelerate much more harmoniously with a better power development under load.