bmp01

That side of the carb is called the metering chamber, coz that's the side that controls the amount of fuel going thro the carb. .. Was it bone dry when you took the cover off? If so that tells you there was no fuel getting through. Now you need to figure out why. Don't touch that brass coloured screw - that's a jet which will limit the fuel flow to the high speed side of carb. The little Lever with the spring under it operates a valve - push down gently on the lever and you'll see the valve bring lifted. Does that work? The end of the lever should be flush with the face of the carb, when the spring has returned it to its rest position, is it? Also, as you can take decent pictures, take the cover right off, turn it over and post a picture of that too. bmp01

A bit awkward. The saw ran fine most of the time but harder and harder to start from cold, eventually it wouldn't. Decent spark with an old fashioned 'jump the gap' tester so I was convinced the problem was fuelling, but that theory started to be less likely when i swapped in a good carb and still no joy. Swapped the plug at some point because it was clear I'd flooded the engine. It started instantly then - just like restarting a hot saw, half way through pulling the cord. Didn't half make me jump I must have swapped that plug in and out 5 times after that, before I accepted the fact the plug was knackered - and thats why I cut it up to see how it had failed. The arcing pattern explained everything. I concluded a damp plug - such as you get when starting on choke - just made it easier for the plug to short out and not arc across the gap. Lesson learnt, just carry a known good plug and put it high up on the priority list of things to swap in when dealing with a PITA engine. bmp01

It's a NGK plug = good quality. I took my ime to dissect it, the swaged section removed in the lathe, then the filler picked out gently. It was visually intact before i started the process. It had racked up tens of running hours, failing in service with the cracked ceramic. It's possible it was subject to handling damage prior to fitting but only to the same level as any other plug. bmp01

Only plug failure I've experienced was recently, with one of those small M10 plugs in an MS211. Ok, so the saw runs reasonably high compression of 195 psi but that's not extortionate and it shouldn't cause a failure anyway. I dissected the plug, ceramic was cracked, nice arc pattern confirmed it was shorting.... see attached pictures. bmp01

I agree saw looks like it is running rich, probably rich at idle too. I bet it is leaning out - that's to say getting closer to optimum - when hanging on the strop, so the idle speed goes up. I wonder if in that orientation - the fuel line is pulling a mixture of fuel and air ie fuel pick up isn't fully dipped in the fuel. ..maybe the fuel level in tank is on the low side? bmp01

As above but if it's sat for a while or had old fuel, it could be a part seized engine and you've got no crankcase pressure to operate the fuel pump in the carb. Whats the compression like on the pull cord? What's the saws history? Has it gradually got worse or completely fine one minute, broken the next? Has it been stored for months on end? Start with the easy stuff, fuel filter, fuel line, impulse line for the fuel pump. Beg, borrow or buy a known good carb to rule that out. You can inspect piston with the exhaust off, that's quick and easy, good one to tick off the list etc. Or take it in for repair / send it to someone to fix. bmp01

But, but.... So 20 thou, 0.5 mm - how much extra life is that going to get you? Compare it with a new bar, how much metal have you got before you run out of clearance, got to be 2-3 mm minimum?? In economic terms you've got; Cost for bar rework to get you 0.5 mm life verse Cost of new bar with 2mm life...so in component costs alone the rework has to cost 1/4 of a new bar. Cant see that happening. bmp01

I would have thought replacing the nose sprocket ought to be economic, it's just driving out a few rivets, swapping out components, riveting - 5 minute job. Rest of the world doesn't see it that way though If the drive links are bottoming out, you've had your money's worth bmp01

Ah-huh, I did manage to break the throttle switch cover on my 211 Ok, so i could have just bought a new cover but this fix allows me to take it all apart without fear of breaking the next cover

You had to take the throttle switch cover off, to get that throttle rod engaged right? I haven't found a way to avoid that step. ...and it always feels like I'm going to break the cover when reinstalling. It's worth checking you've got full travel of both the throttle spindles. Top one (air intake only no fuel) opens later in the application of squeezing the throttle trigger and if it doesn't open fully the stratified charge thingee.... won't be. Plastic contact points wear with usage, on mine i couldn't see any reason not to permanently twist the throttle rod to take up some of the slack, so thats what i did. HTH. bmp01

Nicely put, point taken, i was in two minds about using it, seems ok so far ... 3-4 years. I used a bit of silcone hose as fuel line once. It increased its size 2 fold and lost most of its mechanical strength ie tore very easily. So yes, not very clever to use silicone sealant on the engine despite the tube of goo saying it is fuel resistant. Dirko is spec'd in the Stihl parts lists. If it is also silicone based that's a worry.... Do you know, i think i still have a tube of Hylomar - I'll go see if i can find it and if its stil usable, must be 25 years old Good tip about the cellulose thinners, didn't know that. Thanks for info. bmp01

Red stuff is Dirko, highly rated by all accounts but expensive. I use high temp silicone sealant from Aldi I guess i need to test it for 10 years before i can say its any good. Yeah thanks, been lurking a while, ditto with the US site - thats where I picked up on the different approach to cylinder cleaning. The normal abrasive approach used is emery cloth wrapped around a spindle run in an air tool, sort of flapper wheel. The abrasive cleaning is gaining acceptance there, advantages are speed and no acid to attack of the parent material. I think its ok but possibly needs more care. Oh and you need a lathe if you want to make sanding drums to a specific diameter bmp01

It's all true. T'is the way of the world. Cheap means when it breaks you DONT mend you bin it and buy another. Being a sucker for this kind of thing, I've repaired a few, and tuned them too. My 211 runs a cylinder pressure of 190 psi, achieved by moving the crank centreline ! A muffler mod gives a big gain in percentage terms too. To remove the seized aluminium from the cylinder i use a sanding drum and 120 grit emery cloth. I make the diameter of the drum approx 1 mm smaller than the bore to avoid a too focused abrasion. I try to move the drum around the area of deposited aluminum and at the end of the process put a cross hatch finish in the bore. Pictures of drum and a finished bore attached. bmp01

The clamshell engine only has one split line and that is horizontally through the crank centreline. ... the crank has to come out in order to get to the piston. The basic strip down procedure - remove the front handle, then remove EVERYTHING attached to the engine, apart from the intake manifold and plastic divider thingee. Finally undo the 4 bolts holding engine into chainsaw body, remove engine incl intake manifold etc. Just a note of warning, the engine pan (lower crankcase) is only held on to the cylinder with the sealant at this stage. (Its a s**t design imho, dunno how they are assemble them in the factory with out the worry of the engine falling apart while fiddling it in to the the chainsaw body). bmp01

Actually the Meteor web site is pretty useful, have a look here Meteor Piston Gardening - Forestry Products Catalog I've copied a couple sections from the catalogue, first one is only useful to see the column headings. Second one you can compare the piston dimensions for the MS230 and MS250 pistons. The top of the piston to the gudgeon pin centreline (18) is the same in both cases. The gudgeon pin is the same. Only the diameter and length are different. I'd ask the question to confirm but it looks to me like the MS250 would fit you cylinder spot on. bmp01.

I bet the Meteor piston for the MS250 would be the right one. Stihl spec for the European MS230 says it has the same bore and stroke as the MS250. If it were my money I'd see if the barrel would clean up - it looks genuine Stihl. And ask Meteor directly (Meteor web site has contact info) if their MS250 piston can be used in the Euro MS230. Also ask what the pin to crown dimension is and compare with your chinky piston (but remember your chinky piston isn't guarenteed to be right). That approach costs you under 30 quid. bmp01

Just a thought, what do you know about the saw history, is that the right genuine piston? Rings look pretty free for a seized piston, seized on skirt so lubriction issue - old fuel or straight gassed. bmp01

Yeah, i saw the cast '42' With regard to measurements and from your picture, the piston looks pretty well trashed, do you think you are managing to measure a true diameter using undamaged surfaces? A measurement inline with and below the gudgeon pin looks about the only plausible place.... Apologies if I'm labouring the point ! I have a new piston for a husky here in front of me, made by Golf, (horrible thing but that's another story). Measuring diameters it's 37.78 at the crown, 37.95 on the skirt. It fits a 38.0mm barrel. I also have a seized ms260 piston, heavily damaged on the exhaust side. It measures 44.5 just below the second ring inline with pin (only place without damage), and 43.5 across the skirt ie. 1.2 'ish mm of wear as barrel is 44.7 mm. The way i see it, your piston measures a worn 42.0, you need allowance for thermal expansion, so barrel is probably 42.5 as that matches a MS230 spec. You either need to cross reference part numbers to confirm you have a genuine barrel, measure the barrel. Or just try a 42.5 piston on a suck it and see basis.... I can't help with part numbers, sorry. Look/ask for a parts list. bmp01

Which end of the piston did you measure? Top of the piston is reduced diameter to take account of the expansion as it heats up. Measure the skirt end, in several places and away from the area that seized. And if you can, measure the barrel or find something the right diameter and see if it fits. I expect it is a 42.5 bore, that was what was in the spec. But, I've been wrong before! No idea what Meteor sell for this model. ... If you are lucky you can some times pick up a second hand piston over on that auction site. A used, good condition, genuine piston is a good option in my opinion. Got any ideas why your saw seized in the first place? Good luck, bmp01

Well. .... my first assumption was 'no' You wouldn't change the spec that much and keep the same model number, surely. But i googled MS230 Owners manual - there's usually a spec page at the back of the manual. Hopefully I've managed to attach a screen dump of the spec page. Sure enough there are 2 bore sizes, 40.0 and 42.5 so the answer is 'yes'. Time to have a chat with your supplier? For what is worth; The A stamp I understand to be a tolerance band based on the nominal size. It allows the manufacturer to match up piston and barrel size with out making every batch of parts to a very tight tolerance. So for example if the batch of barrels is 0.010mm bigger than the nominal size, then pistons oversized by 0.010 are used in engine assembly using those barrels. That said, i don't think i have ever come across anything other than 'A' graded. HTH. bmp01

Old engine oil is ..... and for all the reasons mentioned above i dont think i would want to use old engine oil either. Old gearbox oil on the hand isn't (carcinogenic) as there are no products of combustion contaminating it. I raised the question about 'gearbox' oil... Not really of much interest I agree, I only raised the question because the viscosity is similar to bespoke chain oil (unlike engine oil). I'll try it at some point. bmp01

A bit off subject but as we are on different oils, I've got 3Ĺ of used gearbox oil, seems a waste not to use it for something. ... anyone any experience? It's pretty viscous but probably in between regular chain and engine oil, approx SAE 90. No idea if it has any anti fling properties. Probably not good for the environment. Thanks, bmp01

Yep, it is , so it is...

Nope, thats wrong. .. Got a little bit more info. .. Its ARG 6224 (not 4224, which is what i had interpreted too). Goggling ARG 6224 gets a perfect match with a secondhand. .... wait for it.... Sovereign (thats homebase isnt it?) on that auction site, link below. I don't know if that means it's made under licence or more likely a just a rip off of the Komatsu Zenoha. Plastic around the bar nut looks sore/brittle on the eBay one, so that probably explains the need for the alloy plate around the bar mounting. Thought i should update the thread. But all of a sudden I've lost all interest in this SOVEREIGN - USED PETROL CHAINSAW ,WITH 16" - 40 CM GUIDE BAR | eBay