Mazzucchelli full
cheek shaft 54 mm stroke / 105 mm connecting rod - Vespa PK125 XL2 / ETS
shaft with 3 mm stroke for extra bump on all smallframe engines.
These are full cheek shafts to increase pre-compression. The connecting rod has a length of 105 mm (standard 97 mm). The 8 mm difference is usually compensated for with a spacer under the cylinder base, which does not lead to any change in the timing. The 3 mm extra stroke of the shaft can be divided between the base and head gaskets, depending on the desired engine characteristics. All in all, this is a very good way of influencing the cylinder characteristics as desired.
The connecting rod makes a solid impression. The lower bearing is very robust thanks to the silver cage. Particularly with directly aspirated cylinders with a corresponding speed range, care should be taken to ensure a sufficient mixing ratio of oil to petrol to lubricate the bearing. In order to install the shaft, the housing must be spindled accordingly. The cheeks have a larger diameter in order to be able to realize the additional stroke.
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