Racing cylinder 50 ccm, stroke 43 mm
for Vespa 50/PK50/S/XL/XL2/Ape by SIP Scootershop
The 50 cc, 43 mm stroke class serves all short stroke (43 mm) Fuffies. These have the description Vespa 50/PK/XL/XL2 and fit the following Vespa models Vespa 50/N/L/R/S/Special/PK50/S/SS/XL/XL2/FL/N/Rush as well as the following APEs: APE 50/FL/Mix/P50/TMP50.
The differences in cubic capacity
50 cc: The entry into smallframe tuning starts with 50 cc. The racing cylinders all have at least one more overcurrent. This makes them more powerful throughout the entire rev range - despite the original bore of 38.4 mm. Top speeds of 65 km/h are possible. Especially models originally equipped with only 2 overcurrents are brought to life here. Note: 50 cc racing cylinders are also not approved within the German StVZO, i.e. consultation with the local TÜV office is necessary.
75 ccm: Small but mighty! The tuning cylinders with 75 ccm offer significantly more power in every situation due to a 50 % increase in displacement. At the same time, however, the other components are not subjected to extreme stress and the cylinders can be driven excellently with original exhaust systems or the classic bananas. If you like the relaxed Fuffie feeling, but still want to get off the ground better, this is exactly the right cylinder for you. Steep inclines and 2-man operation are no longer taboo zones. Not without reason the most popular class in 50cc tuning. Therefore, there is even a sport tuning in this class. Ideal additions are, depending on further tuning components, the primary gear ratio 3.61 or the tuning pinion from PINASCO (results in a gear ratio of 3.72). If you travel a lot in pairs, you can do without these. In order not to give away any power, the SHB 16.10 carburettor should be replaced by the 16.16.
85 cc: The 85 cc cylinders were developed for the APE cargo tricycles, which are equipped with a PIAGGIO 50 cc engine similar to the Smallframe. These cylinders are therefore very torquey and have plenty of power even at low revs. If they are installed on a Smallframe, they should therefore be combined
with a longer gear ratio that also translates this power into higher speeds. In this combination, the 85cc are ideal touring cylinders.102-112 cc: More is not possible - at least with the original 43 mm stroke crankshaft. The following cylinders exhaust the possibilities offered by the original crankshaft. So if you are afraid to open the engine case, but still want to overtake a truck once in a while, you are in the right place. The 112-115s have plenty of steam, but are more at home in city traffic and on short trips. With the 102s, on the other hand, you can venture out on longer tours. A longer gear ratio and reinforced clutch plates are necessary. Larger carburettors and touring exhaust systems are recommended.
More power for the APE 50
What many people don't know: The cylinders of the Ape 50 are exactly the same as those of the V50/PK50/etc. This means that you can poach unrestrained in the wide field of classic "Fuffituning" to give your little Ape a boost. From the 50cc sports to the 75cc racing cylinders, to the 85cc cylinder, which was originally developed especially for the APE cargo tricycles and provides plenty of thrust for the low revs. Finally, the 102-112 cc cylinders get the maximum out of a Fuffi engine with an original 43 mm stroke - on Vespas, as on Apens. From a displacement of more than 112 cc, a shaft with a 57 stroke is required.