Dellorto carburetor set for us is still the "non - plus - ultra" in throttle response and tunability dar. For Scooter Racing IDSM or Stage6 Cup as a solid solution that works in all weather conditions.
DSSC Scooter Sprint for, should then have the PWK, TM or VHST version 26er, 28er or larger apertures are used. While these are power amplifiers, however, also require a delicate hand and mechanics are much thirstier.

As a principle, one can say that it is undersized at all levels with 21mm never in terms of the durability of the cylinder. It used to be the main jet Dellorto M5.