48mm Big-Bore Conversion Kit for the Husqvarna 257 / 257XP This kit converts the Husqvarna 257 and 257XP to a 48 mm big-bore cylinder, in the 262 class. It includes the 48 mm cylinder, a piston with rings, wrist pin, and clips, the intake manifold, two crankshaft seals, a full gasket set, and the conversion spacer. It relates to Husqvarna part number 503660872. How the Conversion Works The 48 mm cylinder is taller than the stock 257 cylinder, so the included spacer adapts it to the 257 crankcase - that spacer is what makes the big-bore conversion fit. The result is a larger displacement than the stock 257. Fitment and Installation Fits the Husqvarna 257 and 257XP; confirm your saw model before ordering. Installation follows standard two-stroke service procedures using the included spacer and gaskets. Work on a clean bench, confirm ring orientation and port timing, and check the squish clearance during assembly. A piston stop tool and the correct clutch and flywheel tools make removal and reassembly easier.
- A 48 mm big-bore conversion kit for the Husqvarna 257 and 257XP chainsaw. Includes the 48 mm cylinder, a piston with rings, wrist pin and clips, the intake manifold, two crankshaft seals, a full gasket set, and the conversion spacer. Relates to Husqvarna part 503660872.
- Converts the 257/257XP from its stock bore to a 48 mm cylinder for more displacement, in the 262 class. The included spacer adapts the taller 48 mm cylinder to the 257 crankcase, which is what makes the conversion fit.
- Fits the Husqvarna 257 and 257XP. Confirm your saw model before ordering. Because this is a big-bore conversion, the finished displacement is larger than the stock 257.
- Installation uses the included spacer and gaskets and follows standard two-stroke service procedures. Work clean, confirm ring orientation and port timing, and check the squish clearance during assembly.
- A piston stop tool and the correct clutch and flywheel tools make cylinder removal and reassembly easier on this conversion.