45mm Pop Up Piston Kit Fits Echo CS-590 CS-591 CS-600P

A 45mm pop-up piston kit for the Echo CS-590, CS-591 and CS-600P chainsaws and the Shindaiwa 591 and 600SX. The kit contains a raised-dome piston, ring, wrist pin and circlips, and fits where standard piston P021038790 does. The dome reduces combustion chamber volume, which raises compression, tightens squish and helps low-speed torque and starting; it is not a guaranteed gain in top-end power, and for a straight repair the standard flat-top piston is the right part. Cylinders vary, so check piston-to-head clearance with a solder test through the plug hole and choose base gasket thickness from what you measure. Set the high-speed mixture slightly rich, use fresh high-octane fuel and fresh oil, and take the first tank gently. POP-UP PISTON KIT, 45MM - A raised-dome piston with ring, wrist pin and circlips. FITS ECHO CS-590, CS-591 AND CS-600P - Plus the Shindaiwa 591 and 600SX, which share the 45mm engine. It fits where standard piston P021038790 does. WHAT A POP-UP DOES - The dome reduces combustion chamber volume, which raises compression, tightens squish and helps low-speed torque and starting. It is not a guaranteed gain in top-end power; for a straight repair, the standard flat-top piston is the right part. MEASURE SQUISH ON ASSEMBLY - Cylinders vary, so check piston-to-head clearance with a solder test through the plug hole and pick base gasket thickness from what you measure. Too tight and the dome contacts the head. SET IT UP RIGHT - Higher compression runs hotter: set the high-speed mixture slightly rich, use fresh high-octane fuel and fresh oil, and take the first tank gently. Use a ring compressor and check the circlips are fully seated.