Vespa T5 Mk1 Classic SIP PERFORMANCE Long Stroke Crankshaft

rotary/disc valve
stroke 60,0mm
conrod 115,0mm
Race - con rod
Connecting rod bearing: 16x20x23 mm
pin 16mm
valve timing: 125°/-9° post TDC
fine balanced
incl. small end bearing 16x20x23

High end crankshaft with a 60mm stroke, for the Vespa T5 models.

Together with the cylinder and piston, the crankshaft represents the beating heart of any internal combustion engine. It is amongst the hardest working components and the conversion of the pistons stroke to a rotary movement places the highest demands both quality and care taken during construction. The crankshaft should also be well balanced to reduce any unwanted vibrations and the oscillating mass kept to a minimum to support an efficient delivery of the power created by the motor.

60 mm stroke.
115mm con rod.
Balanced inlet porting.

The big-end bearing rotates at the same rate as the motors RPM, receives lubrication from the petrol/two-stroke oil gas mixture and must withstand two abrupt changes in direction of the piston for each motor revolution. The crank-pin, connecting both crankshaft webs with the con rod, has to be pressed into the webs with a certain clearance to the openings in the webs. If this connection is not strong enough the crankshaft can twist and the crankshaft webs become misaligned and seize. To ensure the big end bearing receives sufficient lubrication the big end of the con rod should be provided with slots to facilitate this.

The SIP crankshafts

This new range of performance crankshafts are produced for SIP in Italy and satisfy all of the above listed demands. We have concentrated our efforts to provide the highest quality combined with tried and tested technological features. Each crankshaft is balanced specifically to suit the stroke, con rod length and model of scooter for which it is intended. The 'Performance' crankshaft models include a con rod of extremely high quality and they are made more enduring with an intensive polishing procedure that provides a more stable molecular structure. The smooth polished flanks of the con rod also help reduce turbulence. The polished con rods also have been optimised with a reduction in weight. They possess an gas-flowed profile and have been modified around the big end to improve the bearings lubrication.

The 60mm T5 crankshaft

This crankshaft was developed especially to cater for extreme engine conversions, using the Vespa T5 engine as a basis. Alongside the unusually long stroke for this model, it also possesses an unusually long con rod. This not only increases the smooth running of the motor, but also facilitates easier adaption of tuning cylinders to this length of stroke. The gudgeon pin includes a 16x20x23mm small end bearing. This is compatible with the piston for the MALOSSI cylinder and also pistons from other big-bore kits.

Attention: The crank is made for special cylinders. It requires massive modification for use with common T5 cylinder types like welding and replating. The crankcase does not require machining for this conversion.
The cylinder will require lifting 14mm with a packer, as the con rod is 10mm longer than standard and the stroke will increase the piston travel by 8mm, 4mm up and 4mm down, you may also need to shorten the piston skirt to clear the crankcase.

Conclusion: The ideal crankshaft to shift T5 engines to a higher level. Only for experienced tuners.