A spark plug broke while changing, and part of it fell into cylinder?

Ouch! That sucks. I would avoid taking the head off if you can. A magnet should work, despite what the previous reply said. You can get long, thin, flexible magnets at auto parts stores for a couple of bucks. If you have to take the head off, you're going to spend about $50 in gaskets. If a magnet doesn't work, try using a shop vac and rigging up a tube that you can attach to the end of the shop vac hose, and seal it up with duct tape. A tube that will fit down in the spark plug hole!

Too late now, but the correct thing is to catch the broken bit with some Blue-Tak on the end of a wire and make sure it is all out. The business end of a spark plug is very hard and will have damaged the piston or cylinder bore. There used to be a tractor engine that was started by firing a 12 bore cartridge into the cylinder - "The lead shot passes harmlessly through the exhaust" - but that was a 5 litre single cylinder, so everything was a bit bigger.

well being a mech i can say that u wont get it out with a magnet the spark plug hole is just to small so i would suggest(only if u have the tools and the know-how,other wise take it to a mech)removing the head and the rockers and very carefully removing it! DO NOT scratch the cylinder or the piston,the tiniest difference to the side of the cylinder can be very costly,and DO NOT try to rotate the piston as this may scratch the cylinder!

Nothing gets past the piston head but oil,so manually rotate the engine to bring the piston towards the top.Then get a small hose loose enough to play with,to fit thru the hole.get a vacuum or shop vac.tape the hose to the vacuum hose.Make sure the vacuum is empty before you start so know you got the part out....I did think about a magnet but,the part may be alluminum.

The only way to know is to pull the head. A tiny part of the ceramic body could have been attached to the tip. BTW, spark plug tips are made from stainless steel and a magnet will not attract stainless steel.

if you cant get the piece out with a magnet ,this spark plug cost you alot of money,because you will have to take the head off to remove the piece of spark plug if not you will blow the engine up when you go to start it,so will need to buy a top half gasket head set or new engine.??? up too you..sorry to say....

If the metal tip is still on the small part that fell into the cyl, you can try a magnet

Either try a magnet or start taking the head off.

you should be able to get it out with a magnet.