Echo CS-590 and CS-490 Chainsaw Parts

The only thing these two saws genuinely share is the 50:1 oil in the tank. Everything that bolts to the engine - carburettor, filter, coil, starter - carries a different number, and the chain is a different pitch entirely.

Echo's chainsaw range runs three separate chain pitches, and the model badge does not tell you which one you have. The small CS-310 and CS-352 and the CS-400 class run 3/8" low-profile chain (the 91-series loops). The CS-490 steps up to .325" pitch - its 18" factory bar takes a 72-drive-link loop, genuine chain 20BPX72CQ, and a 20" bar takes 78. The CS-590 Timber Wolf jumps again to full 3/8" pitch: its 20" factory bar takes a 70-drive-link full-chisel loop, 72LPX70CQ.

That is why a chain that fit a friend's "mid-size Echo" will not drop onto yours. Low-profile, .325" and full 3/8" are three different gauges of tooth and three different drive-link counts - the only safe way to re-order is to read the pitch, gauge and drive-link count stamped on the old loop, not the model number. The full method is on the Echo chainsaw chain and bar page.

The CS-590's carburettor is a Walbro HDA-268, sold genuine as A021001661 and found on the CS-590, CS-600P, CS-620P and CS-620PW. The CS-490's is a Walbro WT-1009, genuine A021003391, shared with the CS-4910, CS-500P and CS-501P - a completely different carburettor that looks similar but will not interchange. Searching by the Walbro number rather than the model name is the fastest way to land on the right one.

A saw in either family that won't start follows the same cheap-part-first order as the rest of Echo's two-stroke range: stale fuel first, then the in-tank fuel filter, then the primer bulb and fuel lines, then the spark plug, and only then the carburettor itself. On the CS-590 the genuine 90167Y tune-up kit bundles the air filter, fuel filter and spark plug in one box, which covers three of those steps at once. The full diagnosis order is on the Echo carburetor and won't-start pages.

The CS-590's parts reach well beyond the one model name. The HDA-268 carburettor and the 90167Y tune-up kit list across the CS-600P, CS-620P and CS-620PW, and the recoil starter P021041832 also covers the CS-550P - Echo built this 59.8 cc platform into a whole run of saws and only changed the shroud badge. The same engine was sold under Echo's sister brand as the Shindaiwa 591, which is why Shindaiwa listings turn up when you search for CS-590 parts.

The CS-490 has its own version of this: its A021003391 carburettor crosses to the Shindaiwa 491S and to Echo's CS-4910. As with the smaller saws covered on the CS-400 parts page, the lesson is the same - the number on the part decides fitment, not the name moulded into the plastic.