Trimmer set way too lean from the factory?

[The motor guy]

Got a new trimmer from home depot on clearance for like $250, usually it's $400. Anyways, something seemed off with this thing. Then I realized it was WAY too lean. No wonder it ran like raped ape. This thing was screaming. Well after that other trimmer seized from running a Chinese carb from ebay, I figured we better set this puppy right. I mean even with very little load it still wouldn't 4 stroke. Finally got it set right. Kind of strange. Usually they're good out of the box for the first 50hrs or so.

 

[loneryder]

I think all those small engines are leaned out to meet some standard. My local OPE dealer will adjust the carb after you buy it to run well.

 

[ripcord]

I bought a cheap OPE Hour/RPM meter for getting the high speed mixture roughed in on saws and trimmers... set the low speed mixture and idle speed first so it starts easy and idles nice and then set the high speed mixture so it runs slightly less than the max RPM listed in the documentation (if I can find it) and do fine adjustment after it's good and hot. I run at 32:1 if I'm using regular 2-cycle oil so I usually need to slightly fatten the mix over stock.

The motor guy mentioned "4-stroking" which basically means it's missing a little and the engine makes a kind of "burble" sound at full throttle, unloaded, which indicates it's got a bit too much fuel. This is exactly what you want. It should be a bit too rich under no load because the mixture leans out under load and if you set the mixture to be perfect when unloaded, it will be leaner under load which can cause it to overheat and fry pistons and cylinders. Lean is more powerful, but it drastically shortens the life of the motor.

Lots of modern equipment OPE have tamper resistant adjustment screws but you can buy a set of special screw drivers that allow you to adjust them. Sometimes you need to pop off a plastic cap or two first.

https://www.walmart.com/ip/Carburet...aw-Tool-For-ZAMA-Ryobi-Set-C3-U0R9/2308610155

 

[97prizm]

What brand and model of trimmer? I purchased a Stihl 5 years ago at the end of the summer. The Stihl dealer knocked it down $30 dollars or so and tuned it on the spot.

 

[Cujet]

Some of the new high quality two strokes use a complicated transfer port and carb system (clean air in some ports, air with fuel in others) to eliminate 4 stroking by creating swirl in the combustion chamber AND preventing fuel from exiting the exhaust by the timing of the air ports and fuel/air ports. This of course improves emissions. Husqvarna chain saws are in this category.

My point is that when tuning these, the old methods are incorrect.

What's kind of interesting about these engines is that they make as much or more power than the conventional designs.

Take a look at port and piston design below.

 

[ripcord]

Some of the new high quality two strokes use a complicated transfer port and carb system (clean air in some ports, air with fuel in others) to eliminate 4 stroking by creating swirl in the combustion chamber AND preventing fuel from exiting the exhaust by the timing of the air ports and fuel/air ports. This of course improves emissions. Husqvarna chain saws are in this category.

My point is that when tuning these, the old methods are incorrect.

What's kind of interesting about these engines is that they make as much or more power than the conventional designs.

Take a look at port and piston design below.

So just adjust low speed so it idles and starts well and adjust high speed to give max RPM at full throttle unloaded?

 

[The motor guy]

What brand and model of trimmer? I purchased a Stihl 5 years ago at the end of the summer. The Stihl dealer knocked it down $30 dollars or so and tuned it on the spot.

Echo 2620, most powerful 25.4cc trimmer I've ever used. Cujet, they 4 stroke plenty. I have like 4 of these things

 

[oil pan 4]

Yeah probably, run at least 40:1 two stroke oil gas.

 

[The motor guy]

Some of the new high quality two strokes use a complicated transfer port and carb system (clean air in some ports, air with fuel in others) to eliminate 4 stroking by creating swirl in the combustion chamber AND preventing fuel from exiting the exhaust by the timing of the air ports and fuel/air ports. This of course improves emissions. Husqvarna chain saws are in this category.

My point is that when tuning these, the old methods are incorrect.

What's kind of interesting about these engines is that they make as much or more power than the conventional designs.

Take a look at port and piston design below.

They must run hot then. That little bit of extra fuel is what keeps the piston from melting, atleast that's my understanding

 

[Opelman]

They must run hot then. That little bit of extra fuel is what keeps the piston from melting, atleast that's my understanding

It's called stratocharging. There is a second seperate throttle valve feeding air only into the transfer ports ahead of the air/fuel mix from the crankcase. The idea is to scavenge the exhaust with air only, not air/fuel mix significantly reducing hydrocarbon emissions. Done correctly it seems to work well.

 

[Cujet]

Echo 2620, most powerful 25.4cc trimmer I've ever used. Cujet, they 4 stroke plenty. I have like 4 of these things

Ah ha! I have the same trimmer! It's a conventional rip-snortin' design. Love it. Tune conventionally, but you already knew that!

For some reason I missed what you had.

 

[The motor guy]

Ah ha! I have the same trimmer! It's a conventional rip-snortin' design. Love it. Tune conventionally, but you already knew that!

For some reason I missed what you had.

Yeah echo tends to keep things simple. Everyone owns them like 10:1 around here

 

[E150GT]

Last year I purchased two echo machines I think at the end of the season I'm gonna take them to a dealer and have the carbs adjusted for engine longevity. I wouldn't know a lean from a rich condition

 

[shortyb]

Ah ha! I have the same trimmer! It's a conventional rip-snortin' design. Love it. Tune conventionally, but you already knew that!

For some reason I missed what you had.

The 2620 is an X-series. I thought the X-series featured a stratified design, didn't realize it was conventional port design.

 

[jeepman3071]

All of my Echos were a bit rich out of the box. I've been very happy with each one. I enjoy working on them for customers as well because they are simple and most are well designed. I've pretty much stopped working on Stihl and cheap box store MTD brands. Just not worth the aggravation.

 

[The motor guy]

All of my Echos were a bit rich out of the box. I've been very happy with each one. I enjoy working on them for customers as well because they are simple and most are well designed. I've pretty much stopped working on Stihl and cheap box store MTD brands. Just not worth the aggravation.

I haven't had to touch one yet except for this one.

 

[jeepman3071]

I haven't had to touch one yet except for this one.

The ones I work on are usually not starting from old fuel in the carb, water in the fuel, or in the case of one trimmer the customer let someone borrow it and they ran straight gas through it.

 

[The motor guy]

The ones I work on are usually not starting from old fuel in the carb, water in the fuel, or in the case of one trimmer the customer let someone borrow it and they ran straight gas through it.

Well I meant out of the box

 

[repairman54]

Sure they are lean from the factory, just look at the sticker on it and how many hours it is in compliance.
That sticker is also my quality meter when purchasing, 50 hours or 300 hours, which would you buy?

 

[oil pan 4]

The ones I work on are usually not starting from old fuel in the carb, water in the fuel, or in the case of one trimmer the customer let someone borrow it and they ran straight gas through it.

Yeah I never ever loan 2 stroke anything to anyone, except for one other person.