Piston Skirt

Glad to help The US and non-US versions (and certifications) usually differ, hence the differences in certified bar manufacturers and lenghts as there are some differences in requirements and testing procedures. Originally this chainsaw was designed around A4S chain hence it performs the best with narrow gauge 1/4". The 3/8" laminated Tsumura is somewhat "budget" version. Here are the official sizes from catalogue (20cm is 8", 25cm is 10"):

It is IPX4 certified.

Butterfly type carburettor L controlled ports (3 little ones) are always influencing engine work. At idle usually the closest hole to the engine is open, but starting from acceleration process and up to WOT it sprays fuel from all 3 L ports happier than a race winner sprays champagne. L adjustment always has influence on all RPM range. It is just felt differently on different engines, depending on many factors.

The myth about pencil and NASA has long been debunked. For those "Soviets safer than NASA" I recommend first reading on N1, R-16 and similar rockets and catastrophes. Anyway it is better to get back to the topic.

There is not much extra simplicity in comparison except there is one less solenoid block, wire loom and extra power generating unit. This saves some ~100 grams alone. The lower weight comes from that and from the engine/crankcase design. Actually the push-pull pre-filtration system and oil expansion chambers are a bit more advanced than those found on competitor models so except auto-tune there isn't much where is less techy. Any modern chainsaw model (except those with shady origin) has to pass exactly the same ISO tests for loads from all sides and dropping, so the durability part of the story is a bit of an urban myth.

550XP says 859, but that's apples to oranges as it's major difference in ccs and ultra-major in weight especially if you add the UL Sugi bar which comes stock. Hell, it's even cheaper than 540iXP. MS 241 from the same class is 864 so it's hard to understand where you want the titanium Probably you just don't need 40cc class saw

How much are 543 nowadays in UK?

Understandable. Yet US normally has generally different products and even average American user will normally have different preferences (see lawnmowers, hedge trimmers and even chainsaws of any manufacturer). UK has more in common with Europe so it’s understandable the range and even safety requirements for double insulation is different.

What was/is the issue?

Some of those you see on YouTube in US got there from UK, actually And the most shown one was smuggled to US from Germany. I also see northeast side of Europe selling them for a while already. And it’s hard to forget all the supply mess, especially when other manufacturers wouldn’t even have batteries for most of 2022 worldwide…

Yes. It’s been out for a year already. Looks the same although most of the parts are slightly modified - adopted metal spikes, roller catcher, new way lighter motor & controller. Powerhead weight went down to 2.88kg which IIRC makes it the lightest in this class. The throttle feels a bit smoother too over the trigger travel.

What is exactly “made”? Recently both Stihl and Husqvarna switched from LG & Samsung cells to Sony/Murata, both have their own BMS’es made elsewhere + most of the batteries of recent batches state “Made in Poland”. It might mean plastic casing + assembly, it might also include BMS but in any case the batteries can’t be actually made in-house. Even the BMS will probably contain chips, resistors and thermistors made in various corners of the globe.

Of course it can't be in the manual Current emission laws force manufacturers to do everything anti-tackle so that only authorized hands would be able to adjust anything. Echo dealers are usually trained to do override and adjust the carburetor in 5 steps.

There’s a special procedure of carburettor adjustment for units with a little P in circle next to serial. It has an active ignition coil that compensates ignition advancing to keep the idle steady. To adjust the carburettor the override procedure must be done.

If it's the laser etched model with (P) on it (and large D for idle screw too), then the idle is rock solid 2300 +-50RPM in a very wide mixture setting range. If that one is not stable - the mixture is terribly off.