spudulike

Typical seizes are using old fuel oil mix where the oils lubrication has been degraded, lack of or no two stroke oil in the fuel, air leak or running lean. Running lean can also include split fuel lines, blocked fuel filters, blocked gauze strainers etc The piston crown damage is interesting. It is possible that someone has damaged it using a poor choice of piston stop or it has caved due to the heat. The damage looks like a bad case of pre ignition but that could only happen if the coil had developed a weird fault or the flywheel managed to shear it's key and stop a few degrees in advance. Never seen one that bad before.

I had one of those once, the clutch centre had a clutch shoe retainer lug broken...exactly the same had occurred.

The chain side plates often have a number stamped on them and this can identify the chain type. If you can identify the chain, purchase a meter length and a link so you can make your own, usually by grinding the rivet off and then driving it out with a punch. The link can then be fitted with the closed end facing the rotation direction. Just done a Rover mower which was a 35 ANSI chain...cost around £12 for the link and enough chain for two chains. If you can't identify the chain type then it comes down to roller size, roller pitch (measurement between roller centres) and the width of the chain. Unfortunately, many chains are close in sizing.

I usually push them in as level as possible then tap them in with a suitable size socket as long as it can locate on the edge of the seal otherwise use a reasonable drift and hammer to tap it in. Just do it evenly and match the depth to how the original one was fitted - usually flush with the casing.

You have to know me to know what my words mean. A tad expensive = WTF, do I bend over so you can take me up the posterior, I will have to put the wife on the street corner to pay for that...you have to be having a forking laugh!!!

I do remember some of the yanks modding carbs but the 3120 is relatively rare so never really took much notice of the mod. I have heard of people fitting tights or socks over air filters when milling as the dust will cause wear on the inlet side of the cylinder, doing so will make the saw run a little richer but guess that will be a positive. The foam filter should help you.

The bearings die from lack of grease rather than not using the Stihl grease. Ensure all the grease points are located and filled regularly - weekly if using it every day. Those gears are a tad expensive!!!! Lithium grease is fine.

TBH, Forget all the timing figures but do ensure the saw holds pressure/vacuum and the fuel system is overhauled to ensure the saw doesn't go pop again. You would probably find a bit of a muffler mod and lowering the squish to 0.5mm will up the power but the carb has no adjustment on the H setting making mods a bit more difficult to get the best performance.

That seal is FUBAR, L&S are normally pretty good and will phone if the order is going to be delayed.

I would normally say it sounds like a bit of shyte in the carb gauze strainer but will assume that this was replaced in the carb overhaul. If your saw has stood empty and unused for a long period, it is most likely the fuel line has hardened and isn't reaching the fuel when on its side. You could fill the tank fully and see if it still happens or just replace the fuel line and filter as matter of course and it will probably fix your issue. It is possible the fuel line has a small split/crack in it but the above is probably the best option.

I think he meant the help line.....tough week....big G&T and ....relaxxxxxxxxx

The 340 has the top crankcase moulded in to the lower part of the cylinder making it a typical "Clam" type engine so modifying it with a 346XP cylinder isn't possible. The 350 however, has a separate metal moulding making up the top crankcase and this gives it a flat base where the 346XP cylinder can be fitted and is a known mod although I have never done this. Both the 340 & 350 have a plastic cradle that the metal parts are bolted to and the lower crankcase is formed by the plastic cradle. This IPL will show you what I mean: - 340_340Е_345Е_350.pdf

On the circlips with no tang orientation.....When you purchase an OEM stihl piston, there will be one circlip fitted and the open gap will face upwards to the crown of the piston and that is how I always fit this type of clip.

The tanged ones are easier to fit and remove but the danger is that the tang may wear in time and break. Most of the aftermarket circlips are decidedly iffy at best. Compared to OEM ones, the OEM ones are much harder and springier than the aftermarket ones that can be easily deformed if care isn't taken.

That is strange, the circlip looks like a Stihl one and they never fail. It is most likely that it was either not fitted correctly or damaged on fitting. I usually fit them then rotate so the open part faces the top of the piston and then inspect with a magnifying glass to ensure all is 100%. Very east to think it is fitted correctly but the thing isn't sitting in the groove correctly.

As above. I used an awl and used another screwdriver as a fulcrum but a very similar method. You have to be careful not to pierce too deeply as the ball race is under the seal but it can be done and it works without any major expenditure on special tools.

Try making the L screw a bit richer. The H screw is for flat out running whereas the L screw is for idle to mid revs.

Yup, as OS said, Stihl never used tanged circlips but thanks for the update and glad the saw is up and running again.

Oh bugger....right again!! On removing the seal, you can pierce the steel part and lever it out, use the comfortably expensive Stihl kit....yes, I do have one but piercing it and levering out may be the cheapest way to do it.

Great, glad you got it going and thanks for letting us all know. On your point 5) : - the dry plug will be down to lack of vacuum in the crankcase....the fuel vapour is pulled in to the engine as the piston rises in the cylinder, this causes a vacuum in the crankcase to increase and pull fuel/air vapour in from the carb and enter the engine via the inlet port. Because your piston was so scored, the piston rising in the cylinder caused a substantial lack of vacuum in the crankcase so no fuel on your spark plug. An engine can get a big air leak in the crankcase and still have "secondary compression" (combustion chamber compression) but total lack of fuel due to the above. A bit different from four strokes and is why I bang on about vacuum and pressure testing the engine as well as a compression check on the top end - The crankcase has both vacuum and "Primary compression", the top end is known as "Secondary compression" but is often the only type mentioned.

Yup, ADW pretty much has it and a good recovery by you. The heat drives off any excess water around the saw, best thing you can do. I have seen the needle bearing get a bit rusty when wet so get a bit of lube on it just to make sure

L&S are a decent outfit. I have never had any issues with them over the 12 years of using them. On bit of advice is to fit OEM circlips and make sure they are 100% in their grooves and the gap in the clips is to the top. L&S and Garden Hire Spares are now in business together....Wartec were a GHS brand.

Oh dear, here we go again. How will this one end 🤔

So the "Eggs" nickname lives on to be used again......get well quick but a broken wrist is a bar steward, lots goes on in that joint and full mobillity will take a fair while - the Mrs did hers on a muddy field path....took a while to get it back to normal.

Looks like he has renamed his trading name but that is the fella alright. Usually takes around a week to come in the post. One point - the 038 came in several variants with different size pistons - not a problem if you are purchasing a complete top end kit though.