Echo PB-770T and PB-770H Backpack Blower Parts

If a carburetor listing names only one of the two generation numbers, pull the old carburetor and match the number stamped on it rather than ordering by serial range alone.

Unlike most of the generation splits documented elsewhere on this site, the PB-770T's carburetor doesn't split by a visible spec change - it splits by production run of the same engine. Echo's own parts documentation lists A021001870 (Walbro WYK-345) for earlier-serial units and A021003941 / A021003942 (Walbro WYK-406) for later production. Both generations bolt to the same engine and take the same air filter and starter in the table above - only the carburetor number changes.

The practical approach: if a listing names both numbers, it covers either generation. If it names only one, check the number on the carburetor you're replacing before ordering - that single detail is the one most likely to get a return on this family.

The 770 occupies a tier most people don't realize exists between Echo's two better-known backpack sizes:

• 58.2cc - the PB-580T / PB-580H, Walbro WTA-35
• 63.3cc (this page) - PB-770T / PB-770H, Walbro WYK-345/WYK-406
• 79.9cc - the PB-9010H/T and PB-8010H/T, Walbro WYAB-1

None of the carburetor, filter or starter numbers above cross to either neighboring tier, and none of them cross to the smaller handheld PB-250 / ES-250 either. The one part the 770 does share outside its own family is the spark plug, which is the same physical NGK BPM8Y/BPMR8Y used across Echo's 21-25cc trimmer range and CS-series chainsaws - see the full cross-reference on the spark plug page.

Echo marketed this 63.3cc engine only as the PB-770 pair, unlike the 58.2cc and 79.9cc tiers above and below it, which each run under two or more badges (PB-580 vs PB-580T/H, and PB-8010 vs PB-9010). That single badge is one reason the 770 gets overlooked when people search by model number rather than by displacement.

The PB-770T runs the same 50:1 Power Blend mix as the rest of Echo's two-stroke line - see Echo 2-stroke oil and the 50:1 mix. A 770 that won't start follows the usual order: fuel age first, then the air filter, then the primer bulb and fuel lines, then the spark plug, and only then the carburetor - detailed on the Echo carburetor page.

The 90122 tune-up kit covers the filter and spark plug together, which is the cheaper first move on a blower that has sat since last fall, before suspecting the carburetor generation split above.

Before ordering the carburetor, pull the old one off and read the number cast into the body rather than guessing from how old the machine feels. A021001870 on the body means the earlier Walbro WYK-345; a number beginning A021003 means the later WYK-406. The air filter, pre-filter and recoil starter in the table above don't carry this split - they're the same part regardless of which carburetor generation the blower shipped with.

A blower built for this duty cycle - mid-size commercial lots and larger residential properties - sees enough running hours that the recoil starter and pre-filter are usually the first things to need replacing, well before the carburetor itself.