Sherco Piston Kit - 250cc

Genuine Sherco 250 piston kit, designed for compatible Sherco 250cc two-stroke trials motorcycles. Available in four piston grades (A, B, C and D) to suit different cylinder bore measurements.

Each kit is supplied complete with piston rings, gudgeon pin and circlips, providing the essential components for replacing a worn or damaged piston during engine maintenance or a top-end rebuild.

Piston Sizes & Part Numbers

Size A is the smallest piston grade and is commonly fitted from the factory, although this can vary. Each subsequent grade increases in diameter by 0.01mm.

The piston grade is marked on the crown for identification.

Technical Specifications

• Piston diameters: 72.75–72.78mm
• Recommended piston-to-cylinder clearance: 0.024–0.035mm (2009 Sherco specification)
• Piston measurement position: 19mm above the bottom of the skirt
• Reference measurement temperature: 24°C
• Required little-end bearing: 18 × 22 × 22mm

Choosing the Correct Piston Size

Selecting the correct piston grade is essential for maintaining the recommended piston-to-cylinder clearance.

Cylinder wear may vary throughout the bore, so measurements should be taken at multiple points along its length and in both directions before selecting a replacement piston.

Pistons are manufactured with a tapered and oval profile to accommodate thermal expansion during operation. For accurate sizing, the piston should be measured front to back, 19mm above the bottom of the skirt, at approximately 24°C.

We recommend checking your existing piston grade and measuring the cylinder before ordering, particularly if considering moving to a larger piston size.

Compatibility

Suitable for Sherco 250cc two-stroke trials motorcycles using the M009/M586/M587/M588 piston family.

Important: These replacement pistons require an 18 × 22 × 22mm little-end bearing. The older Sherco M043 bearing is not compatible and must be replaced where fitted.

Please Note

Always confirm your existing piston grade, cylinder measurements and model compatibility before ordering. Piston grades should not be selected solely based on the age of the motorcycle or the size of the existing piston.

If you’re unsure which piston size you require, please contact Road and Trials for advice.