Albero Motore SIP corsa 60 biella 110 a valvola per Vespa 200 45021510

A high-end crankshaft for 200cc Vespa models. Increased stroke combined with the highest quality for torque-oriented, road-going motorized tuning.

Along with the cylinder and piston, the crankshaft is the beating heart of any internal combustion engine. It is among the hardest-working components, and converting the piston stroke into a rotary motion places the highest demands on both quality and the attention to detail required during construction.

The crankshaft should also be well balanced to reduce any unwanted vibrations and oscillating mass kept to a minimum to support efficient delivery of the power created by the engine.

The large end bearing rotates at the same speed as the engines RPM, receives lubrication from the gasoline/two-stroke diesel mixture, and must accommodate two sharp changes in piston direction for each engine revolution.

The crankpin, connecting both crankshaft legs to the connecting rod, must be pressed into the cores with a certain distance from the openings in the cores. If this connection is not strong enough, the crankshaft can spin and the crankshaft webs can become misaligned and seize.

To ensure that the big end bearing receives sufficient lubrication, the big end of the connecting rod should be provided with slots to facilitate this.

The crankshafts available in this range can be divided into two main types. The "Premium" ones feature a high-end "standard" connecting rod, which means its surface finish remains unchanged. They are equipped with grooves and lubrication holes for the large and small bearings, respectively.

The "Performance" crankshaft models include a premium-quality connecting rod and are enhanced with an intensive polishing process that provides a more stable molecular structure. The smooth, polished sides of the connecting rod also help reduce turbulence. The polished connecting rods have also been optimized for weight reduction. They feature a gas-flow profile and have been modified around the large end to improve bearing lubrication.

PX 60mm long stroke crankshaft

The 60 mm stroke provided by the long-stroke crankshaft for the 200cc Vespa models is 3 mm longer than the original crankshafts. This increases the cubic capacity of the installed cylinder by approximately 5%. The improved stroke-to-bore ratio not only increases power, but also significantly improves torque output. The crank is designed to improve torque-rich road engines, and the inlet port timing on the disc valve band is only slightly longer than that of the original type. This allows the engine to maintain decent performance at low revs and is also relatively simple to correctly set up. Backfire from the crankcase is also kept to an acceptable level. The disc valve disc is specially designed to make gas flow through the crankcase more efficient.

Another aspect in the development of crankshaft networks was to provide more effective balancing and a smoother running engine.

Bottom line: The ideal crankshaft for delicate and reliable tuning projects.