High-end Crankshafts for diaphragm-controlled Vespa Engines.
Thomas Dolischka from Austria enjoys a reputation in the Vespa and Lambretta tuning scene that extends far beyond the borders of the Alpine republic. In the tranquil Vorarlberg Rhine Valley, he has realized numerous spectacular scooter projects and developed ingenious special parts for racing. His Crankshafts, which he sold in exclusive quantities as Uncle Tom shafts, became particularly well-known.
- Low-vibration engine running
- Bell shape - ideal for diaphragm intake
- Highest manufacturing quality and first-class materials
For a long time, Uncle Tom shafts were considered to be particularly precisely constructed and reliable. Exact balancing, high-quality materials, tight tolerances, generous cooling slots on the bearings and the characteristic bell shape ensured optimum mixture filling for diaphragm-controlled Engines.
After Thomas had to cease production due to time constraints, the popular Shafts were no longer available. Enthusiastic about the quality of our SIP Performance Shafts, he finally offered to manufacture his Crankshafts again - an offer that we were very happy to accept for these proven and popular models.
Designs and Models
The Uncle Tom shafts are available for three housing types:
- Original Vespa Smallframe housing (51 mm, 54 mm, 56 mm stroke)
- Quattrini casing for Vespa Smallframe (58 mm, 60 mm stroke)
- Original case for Vespa Largeframe (60 mm, 62 mm, 64 mm stroke)
Installation of the Crankshaft
Most variants have exceptionally long strokes. The Crankcase must therefore be spindled and adapted. The rule of thumb is: at least 1 mm larger than the diameter of the Shaft. It is important to ensure that the Casing has sufficient material reserves. In most cases, it is sufficient to spindle the small half of the housing and remove the rotary slide surface in the large half. In the case of smallframe casings, the transition between the crankcase and cylinder base must also be rounded to create space for the Conrod.
Conclusion: Crankshafts that offer ideal conditions for durable tuning in the top performance range.
Technical details
- Bell shape for diaphragm control
- Polished forged connecting rod
- Generous lubrication slots for the bearings
The best setup - SIP-TIPP:
Opinions from experts, customers and the trade press
"... especially suitable for a tuned engine with a reed valve. The special bell-shaped crank web minimizes engine vibrations at high revs."
-Weller Magazine 05, Japan
"I have been riding the 62mm Long Stroke Crankshaft in combination with the MALOSSI Sport 210cc and SIP Road 3.0 on my touring SS180 for 7000 km now: 21 hp, 125 km/h Vmax and 110 km/h cruising speed. Nice power on the mountain, despite my 24 Clutch and very high torque. Perfect. The HardCoriscaTrip 2020 was a pleasure and also puncture-free for me ;-)"
-Alex, SIP Scootershop
"Just like to say very impressed with your SIP 62mm x 127 mm crankshaft, it's been taking 50bhp in its stride with no problem (unlike many others I have tried)."
-Matyn, SIP Dealer
"Top quality and precise workmanship ... characterize this Bell-Shaped Crankshaft with 54mm stroke. I won't compare it with other manufacturers, the differences in quality are too great. The Shaft has its price, and the costs for machining the housing are not insignificant, but the associated possibilities and variants of SF tuning are worth it to me."
-Anonymous, SIP Community
Note: A special Woodruff Key is required for the crankshaft on the clutch side.
