Setting the carb on an ECHO weed wacker

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A guy at work gave me his old ECHO weed wacker (has the curved shaft) that I think is a '92 model. I forget off hand what model it is. Anyways, he had problems with it bogging down intermittently when using it. I found that it needed new fuel lines and a filter, a new plug, air filter, and after replacing all that, I went to use it and the primer ball split. So after fixing everything,I found he had the adjustment screws all out of wack from trying to get it to run right. What is the proper adjustment for these as I've messed with them, but can't seem to get it to run ok...it is either hard to start, or i get it to the point where it starts fine, but then it smokes pretty bad. Most stuff seems to like the idle screw turned in all the way and then backed out about a turn and a half, but I havn't worked on 2stroke stuff to much so I wasn't sure. I don't really know how to adjust the high speed screw. I'm afraid to mess with it and get it to lean and burn it up.
 
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This may or may not be "correct" procedure, but here's how I do it.

1) Start with the high-speed screw. Fiddle around and get it to run well enough to warm up pretty well at no load. Err on the side of too rich for now- protects it from oil starvation.

2) Once its warm, you need about 4 hands. Hold it at high speed, and carefully CLOSE the low-speed screw gently against the stop.

3) Adjust the high-speed screw lean until it runs all-out, then go rich until you get to the point where it JUST begins to "4-cycle". I then back off until the "4-cycling" just stops.

4) open up the low speed screw until you can get it to go all the way down to idle. Work with the low speed screw such that banging the throttle wide-open from idle results in a nice smooth acceleration with no stumbling.

5) Go back to the high-speed screw, and re-adjust until you're right on the edge of 4-cycling (it will probably be rich and ALWAYS 4-cycling at this point because of the added fuel flow from the low-speed jet). Adjust until its just NOT 4-cycling.

6) Re-test acceleration. Should be good to go. You might have to enrich the low-speed screw a bit more to get it to work well when its cold, I've found.
 
Originally Posted By: artbuc
How do you know when it is starting to 4 cycle?


The sound changes. You can tell its firing every other stroke. Its that sound all 2-strokes make... wheeeeeeeeeeBRRRRRwheeeeBRRRRwheeeeeBRRWheeeeeeeeeee

The "BRRRR" is 4-cycling.
 
I got it to atleast start last night, the plug was fouled from the last time I tryed getting it going last summer. I cleaned it out with brakeclean and got it to run, but it would not stay idling unless I choked it a little, so I tryed richening it with the low speed screw, but I could not get it to run after that unless I gave it some throttle. 440 Magnum, thanks, that procedure sounds somewhat like what I heard before, but I couldn't rememeber it correctly. I'll give it a shot. My problem has always been trying to hear it "4cycling".
 
as long as you have it good gas and oil at 50:1 running it lean for a few seconds tuning won't hurt anything.
it most likely has a zama carb, you can read their tech and tuning articles: http://www.zamacarb.com/
http://www.zamacarb.com/tsf_howtoadjustcarb.html

around 1.5 to 2 turns open on both mixture screws will allow you to get the engine running in order to warm it up.
the mixture screws overlap on each other, or one affects the other. there's a few ways you can go about tuning it, here's how i do it.

get the engine running with choke off and warmed up a little, at least 30 seconds of running.

with hi mixture screw defaulted at 1.5 turns open, at idle turn idle mix or LO screw inward / clockwise to lean it out until rpm's drop or engine dies. then open idle screw counterclockwise to richen, restart if necessary, and keep turning ccw till rpms drop and it goes BRRRR (4-cycling). Put idle mix to middle of those lean / rich positions.

give engine throttle easy and hold at full throttle, if it bogs accelerating then turn the hi mixture screw slightly richer or leaner to you get the thing running fast. Once at full throttle, turn hi mixture screw clockwise to lean it out to you hear rpms drop, then turn ccw to richen it and it'll scream again at the ideal mixture point, then keep turning ccw till rpms drop and it does the BRRRR sound from being too rich (4-cycling). turn mix screw to middle of these lean/rich positions where engine is screaming, i generally go slightly richer.

idle engine down, and readjust idle mix screw using same procedure. also adjust idle stop screw to set idle rpm.
go back and forth tuning idle and full throttle mixtures, you should be able to fairly rapidly squeeze throttle and engine should smoothly go to wide open and scream. you may want earplugs.
 
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Originally Posted By: 440Magnum
Originally Posted By: artbuc
How do you know when it is starting to 4 cycle?


The sound changes. You can tell its firing every other stroke. Its that sound all 2-strokes make... wheeeeeeeeeeBRRRRRwheeeeBRRRRwheeeeeBRRWheeeeeeeeeee

The "BRRRR" is 4-cycling.



I got a good laugh out of that. Hey OP, at least be glad your carb is adjustable. Both of my 2-stroke OPE are new and the mixture is set fromt he factory and non-adjustable.
 
Yeah, my dads old YardMan snow blower is like that, it runs ok now, but I have hard time starting it even after its hot unless I give it just a little bit of choke. [censored] thing has no adjustments other than idle speed so I don't think theres much I can do about it unless I replace the carb. He ran some stale gas through it about 2 years ago and its never been the same since, even though I've had the carb off and the bowl off and sprayed carb cleaner through what ever ports I could.
 
I just wanted to thank you guys, I messed with it after work today and got it running good. Smokes pretty good at wide open, but if I turned the hi speed screw richer, it would start to "4stroke", and if I went the other way, the smoke would clear up a bit, but then it sounded like it was running way to fast. Is that ok, does it sound like it should be leaned out a bit? I wanted to er on rich side.

also, now that I have it running, i've been having problems with the string not wanting to come out of the head at times. Mine had the head on it with the single string and you tap the bottom of the head on the ground to release more of it. It will work for a little bit after I rewind the string, but after awhile it gets caught and wont come out anymore. Do I need to just wind the string tighter to begin with? This is my first weed wacker and my when my dad was still alive, he had an old Tanaka with a head that had two strings coming out of it and unfortunately I never paid close enough attention when he would restring it to really know how its done.
 
when it sounds like it is running way too fast, that's when you know you have the carb tuned right. you won't hurt the engine as long as you have a good 2-cycle oil and not a lean mix. I would maybe be worried about the trimmer head that it does not burn out if it's geared and is grease lubricated. I inherited an old poulan PL10 weed wacker and the head gears winged out from lack of lube, and the replacement head which was only $30 was even weak on grease brand new. you might want to check yours if you can pull it apart, i regrease mine every couple years.
If it's blowing oil smoke you may have mixed the gas and oil greater than 50:1 in which case it should smoke a little. I've used echo 2-stroke oil from hdepot, the 1 pint bottle has lasted me for years with just the weed whacker and an echo blower. I would use a name brand oil, stay away from walmart supertec brand or other no name brands.
don't know about the trimmer head and string, they are all a p.i.t.a.
 
Sounds like I have it a little to rich then, I'll try leaning it out tonight. I use the Echo 2stroke oil from Home Depot as well. I bought the little bottles and they said one bottle would make a 50:1 mix with 1 gallon of gas so thats what I did, so I should be ok there.
 
I realize this is a really old thread, but it was exactly what I needed.

I got an Echo SRM-210 free from CraigsList recently, and have been having difficulty with it overall. I got it working, but then it began behaving really strangely - bogging down at what I thought were odd times.

That hidden screw + setting the throttle screw properly definitely did the trick. I had been playing with the throttle screw ad nauseum, and was wondering what the heck was wrong. That was after cleaning out the carb, replacing the fuel lines, swapping the spark plug, and giving the whole thing a good cleaning.

I was out of ideas - and that hidden screw did the trick. Got the weed eater humming along this afternoon!

Thanks to everyone here - I do appreciate the info.

OF
 
I have an Echo SRM-210 trimmer with the Zama barrel carb. I recently also had carb problems. Where is this hidden screw you refer to? I had the carb taken completely apart and couldn't find it.

My solution was to retrofit an older adjustable butterfly carb from a donor GT-2100 trimmer. Now I have full adjustability and I can tune the thing to my liking (and future performance mods).
 
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I have an Echo SRM-210 trimmer with the Zama barrel carb. I recently also had carb problems. Where is this hidden screw you refer to? I had the carb taken completely apart and couldn't find it.

My solution was to retrofit an older adjustable butterfly carb from a donor GT-2100 trimmer. Now I have full adjustability and I can tune the thing to my liking (and future performance mods).
Should be one in between the 2 fuel line inlets by the primer bulb and another in the center of the throttle twist cam thing. Usually just have a rubber plug. You can also just buy a new carb off Amazon if it’s still giving you fits or leaking
 
Should be one in between the 2 fuel line inlets by the primer bulb and another in the center of the throttle twist cam thing. Usually just have a rubber plug. You can also just buy a new carb off Amazon if it’s still giving you fits or leaking
He posted over six years ago. Probably doesn't have it anymore.
 
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