carburetor adjustment on an Echo trimmer

desertbronzeMay 24, 2010

I have a used Echo GT251E two-cycle trimmer. The plastic caps on the carburetor adjustment screws are missing. My son said it would not run at full throttle last week.

I adjusted the screws and got it to run but it is a little rough. What are the correct adjustments for the carburetor?

Thanks for your help.

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ggoyeneche

Run both needles all the way in, but not too tight or you will damage needle or seat or both. Good initial adjustment is 1 1/4 turns out for both.

High speed needle is furthest from engine (near choke or air cleaner) and idle needle is closest to cylinder.

Once warmed up set the idle so it is slow enough to disengage clutch, and rich enough to come off idle without stalling or excessive stumble. High speed jet should be rich enough to allow smooth acceleration without stumble, but not so rich that engine "four cycles" at high speed.

    Bookmark   May 24, 2010 at 11:41PM
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desertbronze

Thanks for your reply.

What do you mean - not so rich that engine "four cycles" at high speed?

Do I need to adjust the large lower screw - the one below the needle valves?

    Bookmark   May 25, 2010 at 12:27AM
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ggoyeneche

"Four cycling" is a description of when the engine runs rich and just begins to miss. Sounds like its now hitting every other revolution, hence the term "four-cycling".

You need to resist the temptation to lean out the mixture and make the engine really "scream". Engine will run too hot, and will probably self destruct.

Although it's not best for emissions (hence the limiter caps), a slightly rich mixture produces the best power and longevity.

    Bookmark   May 25, 2010 at 9:23PM
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