spudulike

Just experience, it often happens on screws that are clean like this. Good job

You can either bypass the CAT by drilling its mount plate if you can get to it or do a cut in the muffler box closest to the cylinder and Louvre it....a bit like the old MS260 used to have. Simple and effective. Don't forget the carb retune.

If the coil is limited, the saw can still run lean. I usually set up the carb and coil rev limiter to kick in at the same time so both limit the top end revs pretty much at the same time.

Ah, can picture it well😉

Glad it went well and everyone's experience helped.

Drills vary in quality....I did ask what manufacturer it came from. Our toolmakers always used Dormer but running to a budget, I have found Heller to be very good and not too expensive. Those screws are not that hard. Cobalt drills will go through a chainsaw bar easy enough.

I reckon that once the drill bites, the screw remains will unscrew as you drill as the screw remains will be under no tension. 2.5 - 3mm drill up it with an easy out in reserve. Relatively easy job. You can sharpen drills very effectively if you have a bench grinder and know the basic angles of a drill head.

If you take the CAT out, I would recommend retuning the carb in case the saw is over revving after removal.

The times I have had petrol saws with a super fast idle in and have found a bit of twig has entered the carb adjustment holes sticking the throttle open. Perhaps nothing has changed with the latest generation of saws!

I would drill it from the other side as that surface will be flat. Those screws are nothing special, relatively soft. Has your drill been used a few times before? Is it a decent brand...Dormer or Heller? Probably a blunt drill rather than the screw being overly hard. You could use a diamond dremel cut off bit to grind a flat on the other side part of the screw but a decent quality drill should go straight through it.

I have seen Squeeze on two occasions,once at Crystal Palace and then at The Stables at Wavendon. They were fantastic and great entertainers, even leading the audience to the bar during the break still playing.

I have a strong liking for a two part putty called "Milliput". You need to thoroughly degrease the surfaces inside and out. You then mix this putty and force it in to both sides of the hole. The putty can be dampened with water to smooth it and it dries hard as stone and is 100% resilient to fuel and pretty much anything else you throw at it. JB weld is also pretty good for repairs like this.

Just do what ADW says, apart from a liking of period dramas he is a fine fella and knows his stuff!!

I bore the outlet hole out so it is still shrouded by the outlet hole cover.

Yup, very common. The first sign is the stop switch not working, the second is a smart arse using the choke to switch the engine off, the third is the same smart arse finding the engine is knackered from their saw tech

I used to open up the muffler in a discrete way so it wasn't obvious and fit a plastic mesh air filter as it gave a decent increase and cost the customer a lot less than a full port job. When you can get good gains from simple mods, you do them and charge the customer for exactly that. Speed is a question of money, how fast do you want to go?

Those metal mesh air filters are pretty poor and years of letting through fine dust can take its toll on the inlet side of the cylinder around the inlet port. The chain spinning on idle is either down to the idle speed being too high or the clutch springs being shot. The stalling of the machine may be down to the idle being run low to stop the chain spinning or the carb being incorrectly set but as I said, a high idle or bad clutch springs are the normal reason for the chain to spin....I would suspect the clutch springs are shot. PM me with where you are but am not really doing much work now.

It will be even less. What brand is this tester? 10 years abuse is good for any saw, invest in a new one and keep the old one as a backup. With 90psi compression, the saw wouldn't run.

You need the top end off (including the muffler and carb), inspect the plating on the cylinder for damage and wear. It may have worn through to the aluminium if the air filter is a wire mesh one. Place the piston rings in the bore checking the end gap. Measure up the piston especially the lower skirt. Replace parts as necessary. If the cylinder is OK (hope it is), try to source a Meteor or Hyway replacement as they are pretty good replacements to OEM. Go careful on the size as there have been a number of variations of this saw. Other than that, if the cylinder is shot, try for a secondhand OEM part or a kit from the same manufacturers as mentioned earlier.

As above, if the saw has relatively low compression, it will drop off further with running and this will cause hot start issues. Other than that, the fuel tank breather can be checked out as if it is semi blocked, the vacuum caused through running may cause an air lock. Also check the carb settings/colour of the spark plug. If the saw is running lean on the L screw, it may be difficult to start when you aren't using the choke. On an old machine, the compression is the most likely as it will have many hours use so it will be worn and may have been nipped up at some stage. You really need 150psi+ when cold, more would be nice. From your description, it sounds like the engine doesn't cut out in mid cut but only when you switch it off or it just stalls when idling. If it was cutting out mid cut flat out, it could be a coil/HT issue as heat can stop the coil functioning if faulty but it could do it mid cut or as yours does - had a 460 once like that and it was the coil to flywheel gap being too large.

Google reckons - Griselinia littoralis.....I reckon it is an evergreen shrubby bush thingy!

Ah, OK, very difficult to tell what the issue is then. All you can do is to do the leak down test, fit the new piston and cleaned up cylinder, check out the fuel system and go from there. When you try to start it, don't use the decomp valve. The extra compression in not using it will help the machine fire.

Has the saw run with the aftermarket kit on it - you can see if the piston crown has carbon on it. If there is plenty of crud around the coil and the saw has run in its current state then it is probably the fuel system. Flywheel keys do shear but it isn't that common. You often get a few backfires or severe kickback when a key goes. Personally I would have whipped the carb apart, cleaned and inspected it and more often or not, that would get it running. You can often tell from adjusting the carb if the saw is leaking air but it does take some experience to spot. It takes a BIG air leak to stop a saw firing completely - I once had one with no seal on the clutch side and it still ran....badly. Make sure the carb screws are out 1 1/2 turns each, they should end up at around 1 turn each once a final tune is done.

It may have already been flooded, the spark plug may be oiled up, the OP may have bunged too much/too little fuel down the hole. I usually stick a squirt of GT85 or WD40 down the throat of the carb, that usually fires most times. Most people don't work in our sort of environments and posses our diagnostic skills so things we do and get the effect we need/want, sometimes just don't happen when tried....look at the compression test....the times people buy an eBay special for cars and big engines and get a poor reading.

You need a device that can produce vacuum as well as pressure - most use Mityvac but you can use home cobbled gauges and brake bleeding kits/bicycle pumps if smart enough. You basically plug all the engine orifices and then push air or draw out depending which test you are doing. Most will use a modified spark plug with a tube down the middle of it or you can feed air in through the impulse connector on some machines. Probably easier to give it to someone that can do the tests. Some plug the orifices, put pressure in to the engine and then dump it in a bath of water - better clear that one with the other half before trying it, especially if they are in it at the time!!