Vertex Sherco Piston Kit - 290cc

The Vertex Sherco 290 Piston Kit is a replacement piston kit for Sherco 290cc two-stroke trials motorcycles. Manufactured by Vertex, these replica pistons feature a cast construction in the original equipment style, making them suitable for engine rebuilds and piston replacements.

Available in four piston grades (A, B, C and D), each kit includes a piston, piston rings, gudgeon pin and circlips.

Piston Sizes

Size A is the smallest piston grade, with each subsequent size increasing in diameter by 0.01mm. The piston grade is marked on the crown for identification.

Technical Specifications

• Piston diameters: 75.95–75.98mm
• Recommended piston-to-cylinder clearance: 0.027–0.037mm
• Gudgeon pin: 18mm diameter × 52mm length
• Gudgeon pin centre to piston crown edge: 29.1mm
• Overall piston height: 68mm
• Piston crown edge height: 4.5mm
• Approximate kit weight: 328g, including rings, gudgeon pin and circlips

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 several points along its length and in both directions before selecting a replacement piston.

Vertex 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.

Important Fitment Information

Some 2011–2012 Sherco 290 models were supplied with a slightly larger piston marked 75.965mm. If replacing one of these, the cylinder should be measured carefully to determine whether a size C piston is suitable.

Piston skirt designs may also vary, with some featuring a half-moon cutout on the inlet side. Check the replacement piston against your existing components before installation.

Compatibility

Suitable for Sherco 290cc two-stroke trials motorcycles using the M245, M589, M590 or M591 piston specifications.

Please Note

Always confirm your existing piston grade, cylinder measurements and model compatibility before ordering. If you’re unsure which piston size you require, please contact Road and Trials for advice.