More power from my weed wackers?

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I have an echo srm225 weed wacker. This year's weeds are out of control due to last Winters rain. It's great on smaller weeds but has trouble with the bigger ones. It calls for 50:1 mix.

Is adding or subtracting oil an option? Would that give it a little more power? Plug gap?
 
I have the same trimmer. Yes, it does well on grasses and small stemmed weeds. It has trouble with the bigger stuff. You may want to look at the blade attachment for it. Changing the plug or fuel mix isn't going to help.
 
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To your first question, in many engines, more oil = more power. At the very least, it will require carb adjustment. Our testing had 16 to 1 as the most practical mixture ratio for power. However, the difference was rather small.

Plug gap won't help

A different muffler with no restriction will help (hollow with larger outlet) . Some of the chainsaw mod guys also own echo equipment and modify them for more performance: https://www.arboristsite.com/commun...mods-srm-210sb-gt-2000-etc.189994/page-4

The bottom line is that it's a 21cc engine and will not make a lot of low and mid range torque, regardless of mods.
It can, however, be modified to double it's original high end output without too much difficulty. That will require a bigger carb, a free flow exhaust and slightly more exhaust port timing and width.
 
A higher hp weed wacker . I run 32 to1 in mine and notice more power, especially when run hard for a long time.
 
I have an OLD Echo SRM-2501 that's a few CCs bigger than yours. Bought it from a neighbor in 1995 hard starting because his kid had injured it on straight gas. New piston, rings, gaskets, removed spark arrestor, gutted baffles from muffler. 24 years later it still SCREAMS. It has a ton of power.

I'd start with opening muffler, gutting it, and adjusting the carb accordingly.

I run mine on Klotz Super Techiniplate somewhere between 40 and 50 to 1

Picture of the old trimmer for fun.

[Linked Image]
 
You could try some .080 line vs .095. Should take less power, BUT you will eat up the line faster.
 
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I bought a new head at Rural King for one of my trimmers that has three blades on it, looks like this:

https://www.homedepot.com/p/Rino-Tuff-Push-N-Load-3-Blade-Universal-Trimmer-Head-16234/100671846

That thing blew through knee high grass and thicker stuff like a hot knife through butter. Mine didn't look exactly like that, it had three orange blades but similar setup.

I bought a new SRM-225 a couple years ago and ended up returning it for the SRM-266. No power issues at all now.
 
Many of the non adjustable carbs have a secretly hidden adjustment in the center of the barrel throttle. Pry or drill the cap and adjust.
 
Muffler mods and richen it will help.I have the same machine and did these early in its life and am pleased.Just below the primer bulb will be a plastic plug over the needle,pull it out and richen it up.About a quarter turn really made a difference on performance.
 
Originally Posted by 92saturnsl2
I bought a new head at Rural King for one of my trimmers that has three blades on it, looks like this:

https://www.homedepot.com/p/Rino-Tuff-Push-N-Load-3-Blade-Universal-Trimmer-Head-16234/100671846

That thing blew through knee high grass and thicker stuff like a hot knife through butter. Mine didn't look exactly like that, it had three orange blades but similar setup.

I bought a new SRM-225 a couple years ago and ended up returning it for the SRM-266. No power issues at all now.


^This
I use this kit from HD on my Hitachi 22.5cc and no longer have problems in weeds or ivy; it even cuts through small sticks with no problem.
 
Just an FYI for those curious, 20cc radio control 2 stroke engines, in a mild state of tune, make 2.5 to 2.8 HP. That's a good bit more than the Echo 21cc OPE engine. That's accomplished via better exhaust and intake. And generally not through high performance port timing. These things have to idle very reliably.
 
Originally Posted by Chris142
I have an echo srm225 weed wacker. This year's weeds are out of control due to last Winters rain. It's great on smaller weeds but has trouble with the bigger ones. It calls for 50:1 mix.

Is adding or subtracting oil an option? Would that give it a little more power? Plug gap?


Look up how to adjust the carb on the internet. Occasionally the screw needs to be turned out a tad. They run too lean from the factory and after about 100hrs from nee they usually quit running and need to be adjusted.
 
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