Echo CS-590 / CS-600P Rebuild Center

The Echo CS-590, CS-591 and CS-600P share one 45mm engine. This page covers the part numbers our kits replace and what to check before you order.

At a glance

Saws	Echo CS-590 · CS-591 · CS-600P Clutch drum and sprocket kit also fits CS-620P and CS-620PW
Bore	45mm
Standard piston	Replaces P021038790 (flat top, stock compression)
Pop-up piston	Raised dome, fits where P021038790 does
Piston kits include	Piston, ring, wrist pin and circlips
Clutch drum and sprocket	3/8 pitch, 7-tooth rim, with needle bearing. Replaces A556001610 and PD5086

Check these four things before you order

The model on the saw. An older metal-case CS600 or CS600EVL is not a CS-600P and takes a different sprocket. Where to find the tag
The cylinder. Look at the bore before you buy a piston. A heavily scored bore needs a new or replated cylinder. A new piston will not seal in it.
Standard or pop-up. For a straight repair, the standard flat top is the right part. A pop-up raises compression and helps low-speed torque and starting, but it is not a promised gain in top-end power. Check squish with a solder test through the plug hole and set base gasket thickness from what you measure.
Chain pitch (sprocket kit). The sprocket is 3/8 pitch only. A .325 or .404 chain needs a different sprocket. Check the pitch stamped on the drive links.

Scored piston, bore is good: the standard 45mm piston kit. Find out why the old one failed first. An air leak at a crank seal or the intake, a lean carburetor or the wrong fuel mix will score the new one.
More compression: the 45mm pop-up piston kit. Set the high-speed mixture slightly rich, use fresh fuel and oil, and take the first tank gently.
Worn sprocket or clutch drum: the 2-piece clutch drum and sprocket kit. Grease the needle bearing, check the clutch shoes and spring while it is off, and fit a new chain if the old one ran on a worn sprocket.