bmp01

Proper knackered. That springing into position around tdc is likely to be the flywheel magnetism and the coil interaction - more noticable when piston and ring friction is low.

MS250 was a clam shell engine, 251 will be the same ... not 2 mins.

Had a post like this not long ago Stihl 211 or 181 or something like that. No real conclusion but along the way I think Spud mentioned WD40 down the plug hole to dissolve / loosen sticky oil from ring grooves. Worth a try, quick and easy.... I guess if your concerned about the mechanics flywheel cover off turn it back and forth - see if it's smooth etc. Presume is not dragging the chain brake, weak or broken clutch spring....

That looks like Screwfix Titan. Used briefly on a HT130, still in one piece after 1/2 tank of fuel, cuts fine on a 0.043 keft chain. I dont expect it to last too long but I'll keep greasing gears while its alive. Details like sealing of oil lines into tank are a bit poor but they do route fom top of tank unlike some that leak until tank is empty.

Looking at video again, not aftermarket bar so probably genuine chain too. Looks like the clutch cover is clamping close to the edges of the bar, over the bar rail area. So are we saying bar profile is different to original (not thickness as I assumed)? And its clamping the bar rails, pinching of chain drive links ? I can see why washer wors in that case, still not nice solution. On a new set up, drive links are a nice (close) running fit in the bar, check for paint over spray or small dings. Short run might ease the high spots. Is the clutch cover nice and flat, not worn or distorted to put undue pressure on bar rails? Is the chain correct number of drive links, shorter would move bar in a tad, small gain, grasping at straws? Might be there is a different (old spec) bar with different fitment you should be using ? HTH.

What is it this "gage"? Thickness of bar changed - maybe so, if you got narrow kerf chain or aftermarket bar... surprised clearances were that small to start with though for the "gage" to bind up now. Are you sure you've got to the bottom of it ? Packing washer - not a nice solution.

L&S have the exploded parts diagrams. Need to log in, navigate via chainsaws to MS250, should have something 10 or more diagrams....

Dress the wheel to regain sharp abrasive and remove metal stuck to wheel ?

I don't have a Husqvarna 44 but I'd be surprised if there is a model specific problem like that. Assuming that's the same pitch and gauge chain that came off. ... I'd question the following: - sprocket wear, light marks on the drive teeth is OK, more than that might be causing the chain to travel in a dogleg fashion between sprocket and bar with a new bar and chain. - is clutch cover binding on clutch/sprocket, might be incorrect assembly of clutch/sprocket or addition of any new parts that have the sprocket towards the clutch cover. Couple of thing to try... Take the chain off, replace bar and clutch cover, tighten cover nut. Does clutch rotate ok ? (Access from below). Put old bar/chain combo on, same binding? Tell us what you learn, hope you find a clue there.

Good outcome. Same symptoms ------> same soln (Ryobi up the page)...

You have a point but.... Its worth considering there's a massive difference between personally owned kit and commercially run kit. Looking at the condion of your saw I'd guess the paper filter never really gets dirty before it's cleaned, which is a good thing not a criticism. Is that the typical saw maintenance? Of the limited number of concrete saws I've seen, 4 off, it was a job to find the paper filter let alone clean it. 2 of the 4 had trashed pistons and cylinders - could have been fuel or filtration issues....or both. Horses for courses, time to let it go....

Back to the concrete saw - the backfire might have done something bad to the carb or it might be a symptom of something going bad with the coil timing and it finally checking out. Glad you checked the flywheel timing. Can you borrow a coil assy from a running saw to fit to this saw ? If its not that I'd do the same swap with the carb but that's a bigger job.

Although its not said directly adw is implying fit a NEW paper filter every time ..... doesn't seem too wrong, concrete saws have just about the worst working environment.

Every day's a school day.

Had the exact same symptoms with a Ryobi saw yesterday. Wouldn't start, stinking of fuel, spark plug properly soggy. When it did finally splutter into life the exhaust outlet was covered in fuel and 2 stroke oil. Saw would rev reluctantly and was unable to idle with out help. Winding in the low speed screw didn't really help, neither did trying to raise idle speed. After the inevitable stall it wouldnt restart, flooded.... Pulled the carb back a fraction with fuel lines still connected - it was dripping, inlet port was running with fuel. I do have a MityVac (with pressure option) so it was easy to see when pressurising the fuel inlet line on the carb that the metering valve wasn't sealing. This saw has a fuel purge bulb so theres a fuel line coming out of the metering chamber - as soon as I put any pressure on the inlet line, fuel and air bubbles came out of the purge bulb line. My point is; I didnt really need the MityVac for this. A short length of hose and a bit of puff would have been sufficient. Would have been a bit trickier if there was no purge bulb but doable. Its worth removing the cover to the metering chamber and repeating the pressure test - that confirms if the valve will seal with nothing pressing on the metering arm. For this saw the diaphragm had gone a bit stiff and taken a set, enough to hold metering valve open. Might have got away with a tweak on the metering arm but that would be a short term fix, new diaphragm req'd. Anyway HTH, be good if the PITA Ryobi eperience can shed some light on this Efco problem.

Does sound like the metering valve (which the metering arm operates) is leaking. Coud be the valve itself - coz its old, corroded, gunked up (and stuck). Or metering arm adjustment out of wack. Or metering diaphragm has degraded enough to be too stiff to operate. That's what I'd understand by "flooding" a cylinder dripping with fuel.

Up the page a bit I said I fitted a Stihl narrow kerf bar and chain - had the clutch cover off at the weekend so cleaned it up took a piccy, see attached. TBH I'd forgotten the detail - you can see it needed new holes in bar for the tensioner and oil feed..... What you can't see is the hole to connect through to the bar rails, bit tricky that one only 1.1mm dia. Chain oils OK but surrounding area is also pretty oily so maybe not sealing too well.... I'll turn oiler down to min.

Yes, on mine the nose sprocket isnt concentric to the bearing, chain tension is all over the shop.

This recent govenment document suggests there's no tax to pay on goods under 135gbp.... Probably too many hoops to jump through for retailers ? https://www.gov.uk/government/publications/notice-143-a-guide-for-international-post-users/notice-143-a-guide-for-international-post-users

From States...and ebay.... global shipping? Whats changed with customs charges on goods from USA ?

Got a sgs clone here, non runner when it came to me...naff fuel lines.... Exhaust has some of that Chinese thick wire wool in it, worth removing. Stihl narrow kerf (1.1mm 0.043") bar and chain improves cutting ability no end. Think I saw an "Archer" branded narrow kerf bar on fleebay for 10 quid t'other day, an ok option in place of Stihl bar. I like it ! On anything upto 6" anyway. But I always check it runs before taking it for an outing....😕

Dunno answer to question but worth knowing seals can be removed and new ones fitted without splitting crankcases. Obvs that goes out of the window if you want new bearings and or new case gaskets. Edit : theres been a few posts on here regarding 346 top ends, quite recently too, anything to be gleened from there ?

Yep, cant promise that's the case for every carb made but typically you can. I'd head over to L and S Engineers as a first port of call, have a look at the exploded parts diagrams.

+1 And with that tiny bit of knowledge the minimal pollution become next to zero..... If its smoking into the room after the stove door has been open for a few seconds its time to get the flue sorted out.

Clearviews pointed to flue height - there some logic to that. The height of the flue directly affects the amount of draw the fire sees, its a strong factor that can turn a good stove into a crap one and vice-versa. Certainly a 4 storey flue is a little out of the norm. Presumably you've got a flue liner in the chimney, was it fully insulated too? Both will add to make the flue draw more strongly. Could be you have too much draw sucking excessive air through the stove.... Not sure about this in modern stoves but have you heard of or looked into having a flue damper fitted? Used to be common practice on old stoves, Rayburn cookers etc to have a flue damper which essentially blocks a big percentage of the flue pipe. That in turn reduces the 'suck' on the stove and slows everything down. Flue damper should only be operated once the flue is up to temperature. Might be frowned upon in this world of 'clean burning' and 'health and safety' but used right it gives a further beneficial control.