The standard DNA carb has the usual "Hyper2" brass washer in the inlet area. When this washer and the rubber air inlet snorkel into the air filter box are removed, the carb needs rejetting with a larger main jet and pilot jet. We used 36-38 pilot (standard is 32) and 74-76 main jet (standard is 56) when we fitted a LeoVinci ZX exhaust system. With this setup power is up to around 6.5bhp, compared to 3bhp when restricted and 5bhp when derestricted. The transmission rollers need optimising (5 to 5.5g) and stronger clutch springs need to be used (or an aftermarket clutch fitted).

If you are going to use a 70cc cylinder kit, the increased power at low RPM means that the standard clutch does not need modifying.
To increase the performance further fit a 70cc cylinder kit, a gear kit and transmission pulleys (Malossi front pulley and torque driver rear pulley half). Because the standard carb is 17.5mm this is large enough for road tuned engines.
Malossi make both cast-iron and aluminium MHR replica cylinders. The latest Malossi cylinders have smaller spigots so that they can be fitted into the smaller Hyper 2 crankcase area. The MHR cylinder is more powerful. This is what we used to obtain graph 2 below.

DR cylinders have a larger bore at 48.0mm and the normal spigot size, so if a DR cylinder is used the crankcase will need altering to remove the anti-tamper crankcase ‘bulges’. Other cylinder makes will need checking for suitability. The latest Malossi front pulley and torque driver rear pulley improve the transmission quality so that the engine RPM remains more consistent throughout the speed range and therefore maximises the acceleration.

This Gilera DNA 50 tuning guide should be read in conjunction with the Hyper 2 tuning guide please click the link below