spudulike

Like I said, my thinking is the big end cage has cracked and spat a bit out and that is what is lodged in to the squish band. It will need a new crank if I am right but it is easy enough to check it out. Looks like the cylinder may have survived which is extremely lucky.

Leave the plug out and pull the engine over briskly to eject any oil there may be in the cylinder. Replace the plug, check the oil level and if OK, fire it up and all should be good but check the oil level after a few minutes running. At least we got to the bottom of the creamy oil A bit of white spirit or even petrol would be better to purge it of oil. Soapy water if just dirty with dust.

Looks like the white metal big end cage may have cracked and spat out a bit hence the dent on the piston crown. You can check the cage, where visible, for damage. The cost of the crank and new bearings will be relatively high, the top end doesn't look too bad in the pics and as BMP said, relatively big job for a novice and hope you have splitters, thumping the crap out of the cases and crank isn't dignified!!

I agree with Dan, sounds like emulsified water and oil, the type of thing you get on your car oil cap when the head gasket has failed or water has got in to the oil on old oil. Clean it off, check the oil in the sump is OK, run it up and get it warm, drain the oil and see if it is nice and clean. You can check to see if the crankcase breather runs back in to the air filter...mostly done to improve emissions.

Not being funny but....that is one massive T bar for the small T27 bit. I have always used the Stihl T27 T bars - pretty strong and last well plus they reach down the cylinder head to the retaining screws at the bottom.

Being someone that knows when an item is fully deceased, how about fixing the beloved item rather than discarding it?

That was my opinion as well. You need ear plugs and ear defenders with this "muffler"! Not something you can really use unless your work is forestry or in the middle of nowhere. Makes my mods seem pretty quiet.

Lived in one for 18 years, we applied to change all the windows when we moved in and found out that there was no need. It may be more "exciting" if the building is protected or listed but if your plans are in line with the original construction, there should be no problems especially if others have done similar. You may find there are TPOs in place etc but it is generally fine as the control protects the look of the area.

Probably either the clutch spring has failed and this would show itself as the chain spinning on idle or the clutch drum bearing has failed. Both relatively easy and cheap to fix. If the clutch bearing has failed, check the oiler arm is still locating on the clutch drum and the end hasn't worn off. Seen this before on numerous MS261s.

That should sort it. Take a lot of care on how the diaphragms and gaskets are fitted. There are two types of carb but guess you know that...not sure if the same carb kit fits both. Just make sure the spacer gasket is fitted between the diaphragm with the metal disk on it and the carb body and make sure the thin polyester pump diaphragm is fitted touching the carb body. Make sure the metering arm is adjusted correctly for height and the spring is located correctly and square. Beware that the gaskets may have been fitted the wrong way round in the past....seen that before!

Seen quite a few with the crack between the mounting screw turrets, not with the chunk missing. The heat causes expansion and eventually cracks the underside of the muffler like in your case.

Bark doesn't look right for cherry but the wood going yellow like that reminds me of hawthorn.

Worth plugging it in to CST to see what fault code comes up.

Probably easiest to keep digging out the rhizomes and spraying any new growth with glyphosate. Do it both sides if the neighbour allows it. We had similar, wife's great idea to hide the log store, 5 years later...bloody jungle with shoots popping up all over the place. 2 years later....all dead by way of the above method. I can see the neighbours point of view but he can't say too much if you are actively sorting out the issue....it takes time though!

Most tanks for build pressure and it isn't always that obvious that the needle is leaking as the fuel can enter the engine rather than flooding the air filter. Anyway...just service the carb as I said. You can check the valve with a pop off tester or Mityvac but won't be 100% conclusive as the fuel tank can build up a lot of pressure.

Ah, it is that new then....check out my comments on temperature of fuel etc. Unlikely the carb has the issues I mention.

I never know if accidents where you don't die or get maimed are good or bad luck. Sure, it is bad luck the blind woman pulled out on you intent on killing you and your loved ones but good luck no one died although I would swerve the next credit card statement, delayed shock isn't good!!

Normally this type of leaking out of the back of the carb is down to the needle valve leaking which may be a faulty needle, weak spring, badly adjusted metering arm or the metering diaphragm has gone hard or baggy. A new carb kit should do it. The hot weather can bring this issue on. If you fill your tank in a cool garage with cool fuel and then leave the equipment in a hot van or in the sun, the pressure will build in the tank and show up any weakness in the parts I have mentioned. On hot days, filling up on site and leaving your fuel and unused kit in the shade will help just watch out for those types that want a strimmer but have no money and don't want to buy one!!!

I have a trusty Black and Decker corded saw. Around late 80s I reckon. Not too bad TBH and stops the old farts round here getting excited about the noise!! Has cut a fair few cube in its life, just isn't that exciting though.

The pressure or vacuum in the crankcase will be the same as above the cylinder but if you use a converted spark plug to inject pressure or vacuum to the engine, move the piston to below the upper transfers so the pressure or vacuum above the piston is transferred to the crankcase. Remember we are not talking about secondary compression which is the pressure between the piston and combustion chamber once the piston covers the exhaust port during pulling over the engine You can't guarantee carb settings at the factory standard of 1&1. You should always tach a saw or live with recognising the four stroking note when flat out. If the fuel was good then you are left with carb settings/issues or air leak. There are other weird reasons for machines to seize but are not common.

Sometimes you can tell a saw has an air leak by turning in the L screw. Normally the idle speed rises until the engine dies when the screw is nearly in. If the saw has a significant air leak, the idle speed increases as the screw is turned in and stays high even with the screw in with the idle screw not lowering the idle as it should. If you know carbs and adjusting them, this can help diagnose air leaks. A typical pressure test is a good idea. If the saw was set at 1 1/4 turns out on both screws and making around 13000rpm and stable with the throttle held open. It shouldn't have failed if the fuel/oil were good.

What was the saws revs set to? The 026 can go to 14k but as I said in a previous post, 13-13.5 krpm is about right. If the saw isn't revving over these figures AND there is enough oil in the fuel and the mix is fresh, it shouldn't seize. Typically saws seize from: - 1) Bad carb adjustment 2) Old fuel mix or straight fuel with no oil being used. 3) Air leak raising the running RPM of the engine. A Mix of the above can cause a seize and starvation of fuel through carb issues, blocked breather etc can exacerbate the issue if you can actually get the saws speed up rather than bogging down. A Saw seize is caused by excessive heat in the engine melting the piston causing the rings to stick and hold in the grooves and transfer or smear the exhaust side of the cylinder with aluminium.....what we refer to as transfer. the heat comes from bad lubrication and/or the machine running too fast. if the saw was set to the parameters I said and lubricated with a decent oil and fuel mix, this shouldn't happen

Best get it sorted rather than move in and 15 years latter have a sodding great tree stuffed between two buildings and a belligerent eco warrior next door not allowing it to be taken down and something more suitable put in its place. People can be strange and plant trees so close to houses not realizing the size they will grow to or the reach of the roots. Just have a word and supply a decent size ceanothus to replace it...job done. It may be a Himalayan birch, can't tell if the trunk has the tell tale brown stripes or not

If it was locking the drum to the clutch somehow or interfering with the oiler arm then it may stop the saw at low revs. These engines don't make much power at idle speeds and a slight impingement will stall the engine. Just a case of removing the drum and clutch, replacing the spring, clearing the broken parts, reassemble and test.

I have seen the top collar break up on these engines. The valve clearances do need regular adjustment. If the engine feels difficult to pull over, the valves need adjustment. The large valve gap knocks the auto decompressor out so you feel the full engine compression if the gap is too large and is an easy way of telling it is out. The OPs machine.....strip it down, see what parts are needed and if uneconomical, sell it on or strip for parts to sell on. It is a bit catastrophic when a valve drops but you may get away with a small repair bill if very lucky. Good learning curve and make sure you set the correct valve timing when rebuilding.