coppicer

Happy to leave welch plug and check valve alone. Have replaced needle, spring, strainer, diaphragms and gaskets. Think that concludes the evening's entertainment - time to put it all back together!

Was dreading taking off the gasket on the other side, but it came off easily and in one piece. Result! Fuel strainer appeared clean, but replaced it anyway, as well as the gasket and diaphragm. Don't have a 5mm drift to knock out the valve jet.

So far so good, but I don't have the technical experience to be able to comment on the welch plug. Maybe if you set up a thread for the 235 you'll get a response? You may get one here too.

The service manual says to fit a new needle "if there is an annular indentation on the sealing cone of the inlet needle". I can see that the cone is darker, but I don't see an indentation or a groove, so I think this is OK as it is. I mean, I have a replacement, but would it make any difference?

Well, the razor blade was more successful, in that it didn't gouge the metal like the screwdriver and the pick, but it did create micro-abrasions as you can see. Having thought about it, if the replacement gasket sticks to the surface as tenaciously as the previous gasket did, it should create a good enough seal once it's screwed down. I've decided not to worry about it, and will try looking at the needle this morning.

No chisel, but I do have razor blades! Will give it a shot.

Bugger, think I already have ?

The carb kit has arrived. Since I have the new parts, and the old ones have been there for 6-7 years, I thought I'd replace them.I took the lid off the carb to find this. Intact, but a bit messy. I removed the diaphragm, but found that instead of coming away cleanly the gasket had stuck to the body of the carb, as seen below. Does anybody have advice on removing this? Carb cleaner maybe? I have some liquid for removing labels, but worried that it could attack rubber components. I also have some WD40 degreaser. I have had a go scraping it away with a pick and a small screwdriver, but that seems very likely to leave scratches on the mating surfaces. I haven't yet checked the needle.

Thanks spud, shoes have some gunk on them, but it wipes off, and they look shiny underneath, not sure if that's good or bad. Gave it a going over with compressed air, most of the crap on the saw was blown back into my face, looks a lot better now (saw, not face).

It wasn't keen to undo it on "low", but on the highest setting it came off and span up immediately. Thought there'd be more crud behind the clutch, but it's not that bad. I will give it a blast of air later. The crankshaft stub seems not to have any damage, and it has no play or slop. Worm spring likewise appears undamaged. Noticed the pinion of the oil pump. So that's how it fits together. Interesting. Following your suggestion I held the clutch up to the light. I can see gaps between the coils of the springs, so presumably not yet requiring replacement? (EDIT I do have some springs and shoes on order.) I should be receiving a carb kit later today, so I will carefully disassemble and take a look. That should be fun. EDIT: carb kit didn't come. Hopefully tomorrow.

OK, hex shaft to 1/2" adapter has arrived. Going to stick a 19mm socket on it and give it a blast, clockwise. What do the team reckon: 1) Start with weakest strength to protect adapter from shearing, or just give it full wallop right from the off? 2) Use screwdriver or something to wedge under clutch and stop it from turning, or don't bother, and rely on rattle gun to crack it open?

Have seen the chain run at idle a few times, but it seems not to happen very often - thought maybe an LA adjustment issue. Will take a look at springs as you suggest.

@spudulike Thanks for that spud, useful. With regard to your earlier comment about the clutch springs, what would you consider slack - would it be obviously weak? I have fiddled around a bit but the springs don't want to come off, so there seems to be some force left in them...

Mine must be older than I remembered. Have found the manual and it suggests 3/4 and 1 turn for H and L respectively!

Having thought about it using the Makita windy gun is likely a non-starter. I bought it mainly for use with screws and bolts, and the 1/4" holder isn't really designed for shocking off a 19mm nut like this. You can get 1/4" to 1/2" adapters of course, and even 19mm sockets on a 1/4" shank, but I think the chance of it shearing off is pretty high. Thanks to @Will C for the tip. I don't have any starter cord clean or otherwise (clean, in my shed??) or rope, etc. so I'll look into sourcing the little Stihl widget.

Got a Makita DTD154Z, think it's designed more for screws, but might work if I put it in "beast mode".

Clutch drum/sprocket looks a bit worn. There seems to be a piece of wire floating around behind the clutch, attached at one end maybe? Would like to get the clutch off, but not sure how to immobilise piston, as I don't have the Stihl locking strip thing.

Like I told the missus, it's how you use it.

Thanks for that. No, this is a service manual I got recently, no idea where original manual went. ? I can't see anything that indicates whether this is an S121B or a 122B. Can see the C1Q marked on a recess in the carb body, and a "274", but nothing else, so I'm as much in the dark as you are.

spud, re "1&1/2 on the H screw" the manual claims 1 turn is factory, is this not recommended - too lean/rich as a default? I have set to 1&1/2 and it seemed to be screwed out more than that when I wound it in to the stop.

Oil pickup body looks OK to the naked eye. Shone a bright light from behind it, and the holes seem clear. Can't see any way to check oil pump. The service manual says I need Stihl installing tool 1123 890 2202 and upwards of £40 seems a bit expensive for something I may only use once...

I have removed the handle. Saw no longer recognisable as a saw. Starting to sweat a bit. I will check the the carb screws, thank you. Unbelievable amount of crud built up in various nooks and crannies inside.

Just remembered that my dad left me a compressor which has been sitting in a dark corner of the shed since he died a few years ago. Spent an hour finding the bits and reading the manual, connected it all up and - result! Not very good at producing a consistent flow of air, but a little patience yielded results. I then lugged down the saw body itself and blew all the dust off that too. Therapeutic! EDIT: attached photo

Agreed, and I normally would, but I was checking whether the chain oil was being pumped through the oilways. There doesn't seem to be a lot, but some is coming through.

I have been using a Stihl MS181 for 6 years now, and for my purposes it's been a good little saw, despite my never really maintained it. I have taken it into the shop for a service once or twice, but it didn't seem to have any effect on operation - was neither better nor worse after the service. Yesterday, when I started and revved the saw with the bar and chain off, it started to get hot and began to smoke from around the sprocket, so I turned it off immediately and let it cool. I thought it might be a problem with the air-fuel mix, and thought I would take the opportunity to service the carb, as the saw sometimes has problems when revving off idle, as described here. I have already replaced the spark plug and air filter, just in case. While taking the saw apart, I have already found a couple of issues, including the fact that two out of the three T27 screws that are supposed to hold the carb on simply aren't there. ? As I have never taken the saw apart, I can only assume the shop failed to put it back together properly after the service, which (if true) is disappointing. I also can't see any sign of the O-ring 9646 945 0610 mentioned on p.72 of the service manual in relation to the stop buffers (why would a stop buffer have an O-ring?). I was planning to replace all the diaphragms and other rubber parts in the carb. I've cleaned bike carbs before, but not chainsaw carbs and I am surprised that the outside of the carb is so filthy with sawdust, etc. How do I clean this? I don't have an ultrasonic cleaner. I have no objection to going at it with a scraper and cotton buds, but I'm worried that I will just shift the crap on the outside of the carb inside the carb. Perhaps the best approach is to take it outside and give it a good blast with carb cleaner? Any advice or tips on diagnostics/work much appreciated! Dan