Crankshaft SIP Uncle Tom stroke 62 connecting rod 127 cod. 45022700

Crankshaft SIP Uncle Tom stroke 62 connecting rod 127 cod. 45022700

The crankcase must be bored with a minimum internal diameter of d=99mm

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

Along with the cylinder and piston, the crankshaft is the beating heart of any internal combustion engine. It is one of the hardest working components and the conversion of the piston stroke into a rotary motion places the highest demands on both quality and attention to detail 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 revolution of the engine.

The crank pin, 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 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 are equipped with a high-end "standard" type of connecting rod, which means that its surface finish remains unchanged. It is equipped with grooves and lubrication holes, for the large and small bearings respectively.

The "Performance" crankshaft models include a very high quality connecting rod and are made more durable with an intensive polishing procedure that provides a more stable molecular structure. The smooth and polished sides of the connecting rod also help reduce turbulence. The polished connecting rods have also been optimized with a reduction in weight. They have a gas flow profile and have been modified around the big end to improve bearing lubrication.

PX 60mm long stroke crankshaft

The 60mm stroke provided by the long stroke crankshaft for the Vespa 200cc models has 3mm more stroke than the original crankshafts. This increases the cubic capacity of the fitted cylinder by about 5%. The improved stroke to bore ratio not only increases power but also significantly increases torque output. The crank is designed to improve torque-hungry road engines and the inlet port timing on the disc valve band is only slightly longer than on the original type. This allows the engine to maintain decent low-rev performance and is also relatively simple to set up correctly. The ‘blowback’ from the crankcase is also kept to an acceptable level. The disc valve disc is specially designed to make the 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.

Conclusion: The ideal crankshaft for delicate and reliable tuning projects.