Wiseco 4881M07700 Forged Piston Kit 77mm 13.5:1 Compression 250cc Dirt Bike

The Wiseco 4881M07700 is a high-performance forged piston kit built for 250cc four-stroke dirt bike engines. Featuring a 77.00mm standard bore and a 13.5:1 high compression ratio, this piston is engineered to deliver maximum power output for demanding trail and racing applications.

Wiseco forges all of their pistons in-house in the USA using dedicated aerospace-grade aluminum alloy forgings. Unlike cast pistons, forged pistons feature a condensed, aligned grain structure that provides significantly higher mechanical strength, superior impact resistance, and improved fatigue life — essential qualities for high-revving four-stroke engines that see repeated stress cycles.

Key Features:

• 77.00mm standard bore with 13.5:1 high compression ratio
• Forged high-silicon, low-expansion aluminum alloy for superior strength-to-weight ratio
• Armor Glide skirt coating reduces friction and improves scuff resistance
• Chrome-plated piston pin with horizontal slot pin oiling for enhanced lubrication
• Race-only 2-ring design with pressure seal groove for maximum ring seal and compression retention
• Race-ready dome finish with smooth edges for improved combustion chamber flame travel
• CNC diamond-turned finish ensures precise sizing with zero variation
• Compatible with Nikasil cylinder bore compositions
• Forged and manufactured in the USA

Each kit includes one piston, rings, piston pin, and piston pin circlips — everything needed to complete a piston replacement. Note: Gasket kit is sold separately.