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The armature on a corded saw is much larger and heavier than a battery saw so there is much more inertia there when the power is switched off, we used to strap a single leg from a pair of type one chainsaw trousers to a dummy leg, then run a saw into it to show how many layers it penetrated, we had to stop using a corded saw as it could penetrate more layers than the petrol equivalent

I am a little bias so would choose the Husqvarna, that’s not to say it’s better than the Stihl just my personal preference, just do not buy either mail order or you may regret it should you have an issue with it.

I guess it does sometimes come down to price, but bear in mind weather the local dealer is Stihl or Husqvarna for service back up, also check if the Stihl has those god awful filler caps, if so you will hate them after they have poured fuel or chain oil down you legs, just saying.

In answer to the original question, no the mk11 dog will not fit the mark 1 , the shape, and hole spacing are completely different.

I do not think you should/or need to put bigger dogs on a 550 sir.

Thank you for the feed back.

Very harsh, can you elaborate a little, is the competition much better and why?

Stop messing about with it, just lift the cylinder and check the condition of the piston.

The trigger switch is a plunger style variable speed, I would say this is an issue with this switch, it is just a plug and play once you split the two halves.

The Husqvarna models listed all have a remote purge bulb rather than the bulb being integral to the carb, these items are purge bulbs not primers, so when the bulb is depressed fuel in the bulb is returned to the tank, as the bulb re inflates it draws fuel from the carb, the cycle then repeats itself, due to this system you can purge the bulb all day without flooding the carb. Bulbs that re inflate quickly without drawing fuel means the bulb or the hose is split, bulbs that will not re inflate either have blocked filter in the fuel tank, or the screen in the carb is blocked, or the hose is trapped, or some carbs have a non return valve in the carb itself which may not be functional, finally tubes incorrect connected.

This is a coil, or wiring to it issue, you need to check the earth wire as a said before, the auto tune unit takes its power from the flywheel magnets passing 5he coil, it is very important you have a good earth, the wire is secured at the r/h rear of the cylinder, a single m4 screw, if the screw has come loose it gives all sorts of problems.

On a side issue, when updating firmware on the 560xp, it is important to select the correct piston, this begs the question how do you know which piston part no. is fitted, low compression piston or standard piston.

Rattling noises I found was the cooling fan has moved on the motor shaft and is now touching the outer cover, easy fix , remove all the outer screws and the left hand side just lifts off with the hand guard attached,then just press the fan back on, trigger issues are usually due to the magnet coming lose on the trigger.

Unfortunately the part no. on the ignition unit will be the unit on its own which does not exist, it comes as an assembly with the wires and cover so gets a completely different number, both mark 1 and mark 2 will require removal of the carb to ease fitting, and also the flywheel on the mark 1, there will be no need to update the firmware if just changing the ignition unit, the air gap should be 0.3mm, if you need a shop manual pm me.

If it has no spark at the plug ( they do work off speed of rotation, so make sure you give it a good crank ) then it will require a replacement unit, the mark 1 is a little more difficult to fit due to the earth wire running behind the carb. mark 1 has a deco valve, the mark 11 has no deco valve.