STIHL hedgetrimmer HS82 T and R : carburator "H" screw setting???

[Fish]

Yes, cw goes more lean.
I suggested that you swap the carbs so you can know for sure that the problem is the carb.
One carb make have a leaky needle, or incorrect lever height, making it perform differently.

 

[Flatsix]

Hallo again
Sorry but I misunderstood the meaning of CW - I thought it ment counterclockwise, but it means CLOCKWISE.... my mistake (but I have problems with the language English - I am a dutch speaking fellow)

Swapping carburators is not in my skills.

Both machines are brandnew - only used a couple of hours.

The problem here in Belgium is that you find many "specialists" - but very few people really now their thing. The man where a bought the machines knows very good how to adjust Stihl, only the problem is that he has another function now and does not longer do the work in the garage. The one that replaces him is not customerfriendly : he said to me that he had adjusted my "R" rich because that period it was 30°C outside and he would not set it back to normal.
That is why I wanted to adjust it myself, but that seems also not so evident.

 

[Fish]

Turning the high speed screw to the right makes the mixture more lean {less fuel}, and the 2 cycle engines will run faster the farther you lean it out, to a point.
You will reach a point that the rpms stop going higher, and that is getting into the danger area, as running too lean for very long will damage/melt the piston, so the safe range is on the rich side of that adjustment. The use of an rpm meter is advisable.
Then as you go richer the engine will start slowing, and that is where you want to be.

But doing the adjustment on the high screw, you likely will need to adjust the low and idle screws. It should idle well, and have fast response when you hit the accelerator, and not die when it comes back down to idle.
After tweaking that, then go back and fine tune the high screw.

But the high speed screw is extremely critical, and adjusting it to lean will damage the engine. If you cannot adjust it out, then the problem is somewhere.

Which is why I suggested swapping carbs. If the other saw runs too rich, and the other saw runs good, then you know that the problem is in the carb. And can confidently go from there.

 

[Flatsix]

Oké Fish, I understand and know all this, but the main problem on these engines is that there is a rev-limiter that kicks-in. So when you open the throttle you hear the motor going into the rpm-limiter. At 9300 rpm it will be finished and you hear it also that the sound is in the rev-limiter. So not easy to adjust that H-screw.

 

[RevB]

https://static.stihl.com/api/BaOnline/Download/ZBA0458-448-0121-B%20%20%20%20%20%20%20%20%20%2004ZBA/0458-448-0121-B_ZBA_04_02.pdf

Read Operators Manual thoroughly, should be under warranty take to reputable Stihl Dealer. Use 90 octane gasoline minimum plus Stihl 2-cycle o ini

https://static.stihl.com/api/BaOnline/Download/ZBA0458-448-0121-B%20%20%20%20%20%20%20%20%20%2004ZBA/0458-448-0121-B_ZBA_04_02.pdf

Read Operators Manual thoroughly, should be under warranty take to reputable Stihl Dealer. Use 90 octane gasoline minimum plus Stihl 2-cycle oil.

It's a two stroke. Effective compression ratio is at best 7:1, no 90 octane required. Manual ”
If you mix the fuel yourself, use only
STIHL two-stroke engine oil or another
high-performance engine oil in
accordance with JASO FB, JASO FC,
JASO FD, ISO-L-EGB, ISO-L-EGC or
ISO-L-EGD"

Stihl oil not required.

 

[RevB]

It takes years to be able to tune handheld 2-stroke equipment efficiently and effectively by ear and using a tachometer. Not something you can read and just turn a screw. Some are easier than others.

Years? Where did you come up with that? It will take me 20 seconds to teach you. It's not rocket science.

 

[Tiger Small Engine]

Years? Where did you come up with that? It will take me 20 seconds to teach you. It's not rocket science.

I will send all my handheld carburetor adjustments your way then. Will save me a lot of time since you are that good and quick.

 

[StarTech]

He must have some mighty good hearing if he can tell the difference between 11,000 rpms and 10,900 rpms. For me that takes a tach to done that. Even the idle settings should be done using a tach when tuning by the factory service manuals.

Here is an example where the max rpm are drop by 20 rpm though a mx rpm is allow it is still better to enrich a tad.

And this one of the simple tune ups on the Echo line.

 

[Flatsix]

Oké Fish, I understand and know all this, but the main problem on these engines is that there is a rev-limiter that kicks-in. So when you open the throttle you hear the motor going into the rpm-limiter. At 9300 rpm it will be finished and you hear it also that the sound is in the rev-limiter. So not easy to adjust that H-screw.

How to adjust the H-screw when you have a rev-limiter??? At 2.5 turns out (the standard setting) when opening WOT the rev-limiter comes in at 9300 rpm is it should. At 2.1/8 turns out (like it is set now) the rev-limiter kicks in at 9300 rpm. How can you adjust then because once the machine reaches the rev-limiter you hair that sound and no adjusting possible.

Turning more out then 2.5 turns till rpm is just before reaching rev-limiter (say 9200 rpm) has no sense because at 2.5 turns it is already too rich. So I wonder how you can set the ideal mixture with the H-screw when you cannot hear the machine working at WOT like machines without rpm-limitation on it. There it would be possible by me : turning out till 9300 rpm and at the same time listening to the sound- when sound high then slightly reduce (turn out) till sound is heavier and that is it. But with rev-limitation you can forget that.?.

 

[Johner]

Take a micrometer and measure each jet see if a slight difference. Maybe you can't remove the jets?