Racing cylinder 80 ccm for Vespa P80X/PX80 E/Lusso/PX100E at SIP Scootershop
The PX80 engine case corresponds to a PX125/150 engine case with a narrower cylinder base. Original 80 and 100 cc cylinders and crankshafts with 48 mm stroke were used. Currently there are no more standard cylinders and pistons for this engine type. Tuning-wise, the MALOSSI 139 cc and the D.R. 135 cc can be fitted with the original shaft. A good combination is the PX80 racing shaft, a SIP road exhaust and a 24 SI carburettor. If you want to go all out, but don't want to spindle up your original engine, you can fall back on our turned down 166-177 cc cylinders. Here, the cylinder base is turned to fit the PX80 engine housing. However, this also requires a crankshaft with 57 mm stroke and a longer gear ratio.
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.
