Crankshaft Schmitt Sportfreund 44mm stroke 85mm conrod for Simson S51, S53, S70, S83, SR50, SR80, KR51/2

Description

The Schmitt Sportfreund crankshaft with a 44 mm stroke and 85 mm connecting rod is a premium replacement and tuning part for Simson mopeds and motorcycles with M531, M541, and M741 engines. It is designed for stock to medium-power tuning engines, setting new standards in precision, strength, and reliability.

The crankshaft is manufactured in a hand-crafted process, precisely balanced, and finely machined. The reinforced pressed joint between the crank pin and the crank arms significantly increases stiffness and high-RPM resistance. The reinforced connecting rod with a silver-plated bearing ensures exceptionally smooth engine operation, better responsiveness, and higher readiness for high RPMs.

The connecting rod is guided via the lower bearing with silver-plated thrust washers, eliminating the need for small spacers on the piston pin and simplifying installation. Special attention is given to the ignition taper, produced in the original 1:5 ratio, eliminating alignment issues with modern flywheels.

Roundness precision, balance, and bearing quality meet the highest modern manufacturing standards and significantly exceed the quality of stock or mass-produced crankshafts.

Technical specifications:

• Stroke: 44 mm

• Connecting rod length: 85 mm

• Weight: 1380 g

• Balancing factor:

  • ≈ 64 % for piston Ø38 mm

  • ≈ 59 % for piston Ø41 mm

  • ≈ 52 % for piston Ø45 mm

Compatibility:

• Simson S51

• Simson S53

• Simson S70

• Simson S83

• Simson SR50

• Simson SR80

• Simson KR51/2

• Engines: M531, M541, M741

Key advantages:

• Premium Schmitt hand-crafted manufacture

• Exceptional stiffness and high-RPM resistance

• Smooth operation and excellent engine responsiveness

• Silver-plated bearings for longer lifespan

• Accurate ignition taper in original ratio

• Ideal for stock and medium tuning setups