bmp01

This. If you've got the clip off already (top pic shows it still in place...) then yeah if might just be crudded up. Presumably you've composed the belleville washes so they ought to have loosened off.... should slide off....

Nice one. Thanks for the update. Plenty of 'how to's' on carb tuning on here and on t'internet..... Smokey, might be if previous owner was trying to tune out an air leak ( ----> lean mixture)....but don't bank on it, make sure fueling is right or it'll seize again.

So either the idle screw is winding itself in (while you are running the saw away from idle) or you've got an air leak so the throttle can't restrict the amount or air / fuel into the engine. The latter will cause engine to seize if not attended to.

Nah, you haven't got the patience to wait in a 2 hour long queue......

Had similar question a week ago, see here. ... https://arbtalk.co.uk/forums/topic/120859-after-market-seal-kits-carb-rebuild-kits-any-good/

"that’s a Stihl “in house” spec bearing" Hate it when they do that. ... But fair enough, you've not much option and as you say if you're doing one then might well be consistent and do the pair.

"Bearings I’ll stick with OEM, no doubt in them then" ...that's the one place I'd go "aftermarket" if theres a saving, you can often see FAG or INA etc on the OEM part. Buy the same or another top brand part from a bearing stockist... -get the right running clearance, press fit brs are often c3 grade. -don't buy no brand Chinese bearings for chainsaw, ever. -check cage material, piston pin needle brg must be metal cage, clutch brg advisable in metal too.

The expression 'hit and miss' is about as conclusive as I can get with aftermarket stuff. Pistons are better quantifed, Meteor are good, Hyway ok, Vtec and Golf last resort in my experience. But some peeps have fitted no brand pistons and got away with it - maybe long enough to flog the saw. Bearings - establish what you need and source known brand stuff, that's a good saving over OEM while keeping quality. Consider what saving are you making in relation to consequencd of part failing. If it's buried in the engine it'll be a full rebuild at best eg piston circlip. Side screw at 10p vs 2 quid then why not.

Aye, all true. How long to diagnose? I'd guess at under 5 minutes for this one. Chap who did my MOT's insisted on driving car into the test station, said he could tell in the space of 25 meters whether he had to spend time on a car. And before that he had a good feel just from sauntering up to the car, critical eye plus experience....

I don't doubt its all been tried. What is surprising and a little disappointing is the lack of detail. For instance, if the muffler was removed (as suggested) its the work of a few minutes to upload a picture. Ye'know cant even be bothered to confirm if the spark plug was soggy wet or bone dry ? But anyway no point wasting breathe. Bye ? .

Good to hear, the chainsaw and idiot relationship is not necessarily an enduring one In fairness that 'idiot' comment was directed at those offering advice (to work on the saw), not your husband. Good luck, some feedback might help in due course - it's impossible to say with certainty what the problem is at the minute.

Well yeah, but OP explained that was done before asking for advice on here...first post... Putting carb screws back to factory settings is (sort of) undoing tamperring. I'd imagine that was the first thing the chap did after it wouldn't start though. I'm in the 'do the basics' camp before sending back, you'd do that stuff as basic maintenance anyway. Basics: -Reset the carb screws to manufacturers settings. -Has it got compression, pick up by pull cord, does it drop slowly ? -Is there a spark ? (probably ok from the description). -Take the plug out, is it dry or wet/oily? ---If the plugs wet/oily pull the saw over with the plug out to clear it out. Clean the plug (or get a new one), heat plug up, install, try to start. Don't be using the choke too much, choke off at the first hint of it coughing and probably after the first or second pull anyway if it's got a purge bulb. ---If plug is dry there's no fuel getting through. Clean the plug (or get a new one), a few drops of fuel through spark plug hole, install plug, try to start. It might run for an instant before running out of fuel again. -If it doesn't run or runs briefly check spark plug again. Feedback ?

That video is in slow motion, would have been fun if they had done done some cutting. Been caught out several times with a MS211 that's in the family. Pull the cord, nothing seems to happen, about ready to do another drop pull start and all of a sudden the blinking engines running just as you're lifting the saw. Quite disconcerting, I like old school.... I've not tried starting it slowly, just not part of the game plan when it comes to starting an engine.

Use chemicals just on the aluminium deposit, dont soak the whole dammed thing ! Chemicals will eat any aluminium they come into contact with. And in case it needs saying, keep it off your hands and protect your eyes etc, nasty stuff...

Question for Mr Edmonds - did you sell the lot, still collecting dust ? Just curious, sure there are a few others wondering too and it'd be nice to know given the interest shown. .... Ta,

Naah, it's quite gentle, honest. If you think of it like a sanding pad on a flat surface you can see the pressure is quite low compared with a digit (finger) pressing a small area of abrasive. Each sanding drum is bespoke to cylinder size so the curvature is matched as best as possible. Of course there's a bit of operator involvement, no point focusing on a pristine bit of the bore. Tend to use it like a honing tool and get cross hatch pattern, much like a new one.

2 routes: Chemical- disolve aluminium deposits, Abrasion - brake hone / emery cloth on a mandrel or a flappy wheel I don't know that there is any evidence says one is better than the other. For a light seize where there is only a small amount of aluminium to remove I guess dissolving it won't take too long. But check for deep scores in the cylinder, you don't want chemicals to attack the aluminium cylinder under the plating. Personally I quite like the emery on a mandrel but then making up the mandrel is small beer as I have a lathe. See pic. I've used the old blue Harpic (bog cleaner), bubbles nicely on ally, I've used that in the past and seems ok - don't know if that's frowned upon ?

Good pictures by the way ?

Yeah, that's not too good. But also not a complete disaster, as these things go it's a light seize. Really depends how you value your time whether you fix it or bin it. In my opinion there's a very good chance the cylinder will clean up, new piston and ring assembly required if you want to do it right. The engine is not a clamshell design so pretty easy to get the cylinder off. As stated by Spud, you need to think about why its done that in the first place, otherwise it will repeat itself. Could be bad fuel, could be fuel lines or carb. Could also be crankcase seals. You might want to do a bit of research to see what you're up against. HTH.

Well bugger me, just had a play and its actually not all bad. Walbro carb with purge bulb, 160 psi compression cold and some nutter has fitted a new plug and done a muffler mod on it (must remember to value my time better). I dumped the fuel, added some fresh, purged it though and it popped on the first pull. Choke in and it started next pull. Compression was still 150 psi hot, (must have had a new ring surely?) Ok so the AV system let's the vibration through and its probably not got the power of a decent saw but not all bad.

Spud - here you go chap, this is what a Mitox 4116 looks like ? Dammed thing made my hand dirty when I dragged it out from where it was, been there that long. And yes, it was broken and free and I got suckered into fixing it. Part seized, it didn't get any new bits, just the rough edges smoothing off - and that means I can't flog it as a runner really, not worth the aggro.

A bit more time to explain - the 'easy start' thing is just a torsion spring that goes between the pull cord pulley and the engine flywheel, its like the spring used to retract the pull cord only bigger in all dimensions. It's purpose is to smooth out the resistance you feel when you pull the starter cord. Which means you won't feel the engine reaching compression, it will just feel soggy. Personally, I hate it. And it's another thing to break. On the plus side, the theory is that once the engine has gone past compression once the spring releases is energy quickly so the engine is rotating faster during the next firing cycle. .... maybe. .... None of this says your saw isn't broken. But if it pops with some fuel mix down the plug hole I'd say there is some hope. You might be into carb cleaning or fuel line issues. Let us know what the piston is like, a picture will allow a proper judgement. HTH, bmp01

The 4116 i looked at had 'easy start' spring mechanism. It just might be ok even if it feels like it doesn't have compression. Pull the muffler off and check piston as said earlier. ...

I'm not a battery person but my battery drills used to be NiCad and NiMH and we're invariably 'flat' when left for any length of time (Makita, Bosch bought new and not cheap crap). Converted to Li-Ion and wot-d-ye-no always ready to use and much lighter to boot. Much impressed by this battery type.

Here's some back ground reading for you. https://arbtalk.co.uk/forums/topic/65438-mac-cat-839/ You can also use the search feature on here. A couple of points and a start...: -If isn't garbage already, it soon will be if you run it on neat petrol and not 2 stroke mix. Google why you need 2 stroke mix. -The easy start shows the ignition system and engine compression are probably OK, not 100% guaranteed though. -Smoke from a running engine is just as likely from too much fuel (as it is from oil in the fuel). -A crude compression test - pick the saw up by the pull start cord, if it unwinds the cord quick its knackered. If it unwinds the cord slowly with a series of resistances over 15 seconds or more your in luck. Try this with the plug out, you'll see what no compression is like. -If you want to see if bar oil is leaking into fuel tank, empty fuel out, leave oil in. See if the empty fuel tank fills with oil. -I'd try this, plug out - is it wet with fuel? Continue with the plug out, pull the engine over dozen times with choke off and throttle open - gives it a clear out. Dry the plug and if posible warm up the sparky end with blow torch/gas hob. Drop a couple of cc's of fuel mix down the plug hole, fit the hot plug in a hurry and see if it goes (without choke). You can do this over a few times if you want but if it won't run like this for a second or 2 it could be back to the hand saw time. Good luck.