Introduction
The initial assumption with the Gilera DNA 50 scooter is that it is just a water-cooled version of the Hiper2 motor in the Zip 2000 Kat. But the 14 inch rear wheel, the crankcase length and the gear box layout are not the same as used in earlier Piaggio 50cc automatics.
The gear transfer box in the DNA motor is now accessed by unbolting the case area from behind the rear wheel. (Previously this was part of the main crankcase and was accessed through a cover under the rear transmission pulley.)
The DNA is restricted in the usual way for Piaggio and Gilera scooters - a washer in the front pulley (actually two) and a resonant pipe on the exhaust, the effects of which can be seen in the dyno curve below. A main jet increase is needed when derestricting.
The problem with any tuning using the catalysed standard exhaust is that the exhaust gas analyser machines that measure the CO content are not accurate, which makes it difficult to confirm what jetting changes are required when engine modifications are made with the standard exhaust. So, when derestricting using the standard exhaust leave the air inlet snorkel and brass washer in the carb in place, and fit a 60 main jet.

Derestricting a UK Spec DNA 50
First remove the two nylon washers in-between the front pulley halves.
Remove the exhaust front pipe resonant tube (blind-ended tube) and weld over the hole.
Rejet the carb with a larger main jet (standard is 56). Piaggio recommend using a 58, but we prefer a 60.

Additional Performance
The next step is to fit an aftermarket exhaust system. We have found that the LeoVinci Handmade ZX gives an excellent boost in performance when fitted with the appropriate carb and transmission modifications (see Dynojet graph 1 below).