RD Vespa Carburettor Main Jet (SI 20.15-17 A-D/20.20-26.26E/G/H)
The main jet is found at the bottom of the jet stack on the SI Carburettor. The main jet is responsible for regulating the amount of fuel available for premixing. From changing the exhaust to changing the cylinder it is necessary changing the main jet to suit the scooter.
We have a fantastic range of jet sizes available! We would recommend selecting a few different sizes, this will allow you to have a good variation especially when you are tuning engines.
Comparison No. 4576 (DELLORTO)