MS 440 rebuild and modifications

[Philtreeman#1]

Howdy everyone
I finally got my MS 440 disassembled. I am planing to do a few modifications. dual port muffler, remove mixture screw limiters, try a timing advance & maybe some port work. I will post some pictures. If you are working on a 440 you are welcome to post here.

 

[Philtreeman#1]

OK first question for you saw experts; The saw is fifteen years old and the cylinder walls are smooth (no cross hatch left) and there are no scratches. Do you recommend honing the cylinder and replacing the rings or just replacing the jug and piston. I did not keep track of the rings when I disassembled it. I tend to like to do things right when they are apart, rather than having to go back and repair later.

 

[SixGun]

Keep your OEM cylinder if possible. If there are no scratches and no scoring I would just run some scotch bright through it and replace rings with Cabers.You could replace the piston for good measure if you want. I would strongly recommend OEM Stihl or Meteor and replace piston bearing while its apart. Also you can get some great gains in compression and power by leaving out the base gasket and using a sealant instead. Just be sure to check your squish if removing gasket. There are lots of great vids about checking squish on Youtube.

 

[Philtreeman#1]

Thank you SixGun I got the parts ordered. New meteor piston and rings. I checked sqish with piece of solder before I disassembled, it had .030. After removing gasket it had zero clearance. What do you suggest? Should I have my local engine shop remove some material or use something to space it?

 

[SixGun]

You could have them remove some material but unless they do cylinder work regularly I would be careful who does it.
In my opinion, you are looking for about .018 to .020 clearance so try to find a gasket material that will leave proper space. There are lots of options for gaskets from beer cans to manilla folders or brass shim material available online.
This is a cheaper option than machine work and works fine, just use an anaerobic sealant for good measure when assembling and check final squish numbers before running. Also do a vacuum test.