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hi all, can someone tell me what the lo and hi rpm of most string trimmers? what rpm should they idle at? thanks.

pete g said:

hi all, can someone tell me what the lo and hi rpm of most string trimmers? what rpm should they idle at? thanks.

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I looked it up (since I didn't know the answer either), and this one website said this:
"Weed eaters have a RPM of the range 3,000 upto 15,000 RPM."
(What are the average RPMs of push mowers, weed-eaters, chainsaws? Feel free to include any other small motor items most people have lying about the garage. (Torques too if you know them) | Answerbag)

pete g said:

hi all, can someone tell me what the lo and hi rpm of most string trimmers? what rpm should they idle at? thanks.

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7000rpms is a pretty decent amount. it wont fray the ends of the line and if you hit your jeans or your boot it wont slice through it!!:laughing:

pete g said:

hi all, can someone tell me what the lo and hi rpm of most string trimmers? what rpm should they idle at? thanks.

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Most of your string trimmers like Echo and such are going to be around 2700 to 3000 rpm lo Idle speed and your High speed is going to be 10,000 rpm. Stihl Lo rpm is 2800 high is 10,500 for the 4 mix units. If you are using a cutting tool the max is 7500 rpm. It should tell you in the manual for the machine if you have it. As a rule of thumb you can set the low idle until the engine runs smoothly and the trimmer head doesn't rotate, if the head spins the idle is to high.

thanks for the response, guys. pg

pete g said:

thanks for the response, guys. pg

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What type trimmer do you have or trying to set up?

Ric said:

As a rule of thumb you can set the low idle until the engine runs smoothly and the trimmer head doesn't rotate, if the head spins the idle is to high.

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I have an Echo GT-2100 that was purchased around 25 years ago. When I use it I noticed that when it is at "full-throttle", it sounds a lot more powerful and more "revved up" than my new SRM-225 at full power. Also, when it is idling the head does spin. So from what you said that means that the idle rpm is too high, and maybe that causes the "full-throttle" rpm to be too high also? Correct?

lawn mower fanatic said:

I have an Echo GT-2100 that was purchased around 25 years ago. When I use it I noticed that when it is at "full-throttle", it sounds a lot more powerful and more "revved up" than my new SRM-225 at full power. Also, when it is idling the head does spin. So from what you said that means that the idle rpm is too high, and maybe that causes the "full-throttle" rpm to be too high also? Correct?

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If the Trimmer head spins then the idle is set to high, the clutch should not engage at idle. You have a idle adjustment, high and low speed adjustment screws on the 2100. If you adjust the idle to the point where the head just starts to spin then back it off so the clutch doesn't engage or spin the head, you should be running some where around 3000 rpm and that should not have any effect on the top end speed of the unit.

Ric said:

If the Trimmer head spins then the idle is set to high, the clutch should not engage at idle. You have a idle adjustment, high and low speed adjustment screws on the 2100. If you adjust the idle to the point where the head just starts to spin then back it off so the clutch doesn't engage or spin the head, you should be running some where around 3000 rpm and that should not have any effect on the top end speed of the unit.

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OK thanks for the info! :thumbsup:

Ric said:

What type trimmer do you have or trying to set up?

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its a sears/poulan 32cc. model 358-791510.

lawn mower fanatic said:

OK thanks for the info! :thumbsup:

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Got a question, What oil mixture are you using in that 2100?

Ric said:

Got a question, What oil mixture are you using in that 2100?

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Just 1 "can" of the Echo Power Blend for 1 gallon of gas...I hardly EVER use my 2100.

lawn mower fanatic said:

Just 1 "can" of the Echo Power Blend for 1 gallon of gas...I hardly EVER use my 2100.

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You said you noticed that when it is at "full-throttle", it sounds a lot more powerful and more "revved up" than my new SRM-225 at full power. If you are using a 50 to 1 mix and that thing seems more revved up it may be your running the wrong mix. Those older units ran something like a 30 to 1. You mite want to do some checking on the mixture, just sayin. Just for grins I'm going to see if I can find a manual for that thing.

Ric said:

You said you noticed that when it is at "full-throttle", it sounds a lot more powerful and more "revved up" than my new SRM-225 at full power. If you are using a 50 to 1 mix and that thing seems more revved up it may be your running the wrong mix. Those older units ran something like a 30 to 1. You mite want to do some checking on the mixture, just sayin. Just for grins I'm going to see if I can find a manual for that thing.

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Oh, OK. Here is a picture from another thread of the oil I use (just so you know)...http://www.lawnmowerforum.com/attac...352050206-new-echo-oil-red-armor-dscn1174-jpg

lawn mower fanatic said:

Oh, OK. Here is a picture from another thread of the oil I use (just so you know)...http://www.lawnmowerforum.com/attac...352050206-new-echo-oil-red-armor-dscn1174-jpg

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That's a 50 to 1 mix and that's OK for the new units but may not be for that 2100. I just looked up the manual for the 2100 and it said a 32 : 1 ratio with Echo oil or a 50 : 1 ratio with special oil approved by Echo. Now if that means there new oil, I don't know.

You can look up the manual here: http://www.echo-usa.com/Support-Help/Technical-Documents.aspx?s=GT-230&acc=true&c=en-us Just put GT 2100 in the Document search box, then click on the operators manual.

Ric said:

That's a 50 to 1 mix and that's OK for the new units but may not be for that 2100. I just looked up the manual for the 2100 and it said a 32 : 1 ratio with Echo oil or a 50 : 1 ratio with special oil approved by Echo. Now if that means there new oil, I don't know. View attachment 9885

You can look up the manual here: Operator Manuals, Safety Manuals, Parts Catalogs, Safety Videos | ECHO USA Just put GT 2100 in the Document search box.

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Hmmmm....yeah I don't know what that means. I am not really worried, though, because if the 2100 gets used twice a season it's lucky. I always use the SRM-225.

lawn mower fanatic said:

I have an Echo GT-2100 that was purchased around 25 years ago. When I use it I noticed that when it is at "full-throttle", it sounds a lot more powerful and more "revved up" than my new SRM-225 at full power. Also, when it is idling the head does spin. So from what you said that means that the idle rpm is too high, and maybe that causes the "full-throttle" rpm to be too high also? Correct?

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The GREAT Ryobi 790R I had for 10 years of brutal usage just died. (Flywheel/coil cost prohibitive) Critics bash such units as "1/2 crank," which may refer to lack of a second main journal (comments).Anyway I do believe lack of location did kill it when flywheel touched coil.

After weeks online staring at pictures I bought a discounted 31 cc Sears because it resemble the 790r. Behold, I have the unit and "may" be able to click in the bottom part of the old unit which includes a bolt on- brush blade. The new unit chokes at full throttle, but is very strong at 8/10s. I notice it does comply with some EPA emissions. It reminds me of auto engines in the 70's which were leaned out beyond reason. I can see that the new carb has sealed main jet, no adjustment. Maybe I can do a transplant. The low rpm does not change the high rpm. I have read the upper rpm is typically
7000, but perhaps some of the 26cc units can hit 10,000. Race 2 strokes go 17,000 & beyond.

The Makita cordless string trimmer is best it runs between 5,000 - 6,500rmp
For gas expect slightly more power and variable speed around 3,100 - 8,220rmp. Dont need such low speed settings though.

Pinkchick- Don't expect too fast of replies to this thread, it was from Nov 25/ 2012

My gas / mix Shindaiwa revs to 10,000 rpms. And is smooth as glass.