Racing cylinder 125-150 ccm, 2 ÜS
for Vespa 125 VNB-Super/150 VBA-Super 1° at SIP Scootershop
Customers ask - SIP answers
"Why do I need to increase my jetting when cylinder or exhaust tuning?"
Engine tuning always increases the air requirement of the engine. The old fuel injection system would not be able to supply the necessary amount of fuel for the increased air flow. If the engine were operated with the old (=too small) fuel injection, the "produced" mixture would be too lean and the engine would run hot. Pistons and/or cylinders would be at risk of rapid heat death. It is therefore very important to adjust the fuel injection when fitting a tuning cylinder according to the manufacturer's specifications. Often it is sufficient to replace the main jet.
