Ms 260 Piston Help

[Vintage Engine Repairs]

hi guys,

Looking for the size of piston required for my saw. Seems there are different sizes depending on the age of the saw. It seems either 44mm or 44.7mm piston depending on the age of the saw

Well my piston measures 43.8mm and the cylinder measures 44mm Therefore I’m confused as to what size I need. Will a 44 fit in a 44?!

Gunna try reusing this cylinder, cleaned it up as good as I can, and the marks there, I can only feel one or two just the tiniest bit under my nail...

 

[cuinrearview]

I think you could clean that jug up a little more but it should be fine as is.

Why wouldn't a 44mm piston work in a 44mm cylinder?

 

[Vintage Engine Repairs]

I think you could clean that jug up a little more but it should be fine as is.

Why wouldn't a 44mm piston work in a 44mm cylinder?

Would you go at it with some more abrasive paper? I have tried acid which didn’t work for me.

I figured if two things are the same size, they won’t fit into each other ?!

 

[mkinslow]

44mm will work. All pistons and cylinders measure out that way

Sent from my SM-G892A using Tapatalk

 

[cuinrearview]

Would you go at it with some more abrasive paper? I have tried acid which didn’t work for me

Yah hit it with some 500 and red scotch brite.

I figured if two things are the same size, they won’t fit into each other ?!

The difference is thousandths of an inch. Is what you are measuring with THAT precise??

 

[pioneerguy600]

The pistons are called 44mm but actually are undersized a few thousands, there are only OEM 44 mm or 44.7 cylinders on the 260`s, run a 44 in a 44 mm cylinder, the factory takes care of the clearance issues. Once a cylinder has been used I have no issues using any piston variations of A, B or C stamped piston in them. When a new set is bought as a set then they come with matching stamped P&C.

 

[frank_]

8" thou (.2mm) is a lot of clearance, where are you measuring the piston tom ?

 

[Vintage Engine Repairs]

I measured the piston at the top, above the top ring although that was on some pretty poor analogue calipers.

 

[pioneerguy600]

The top of a piston will be of smaller diameter than the skirt, it will expand more up there as it has more metal/ density.

 

[frank_]

I measured the piston at the top, above the top ring although that was on some pretty poor analogue calipers.

the lower skirt is the critical clearance because the piston is tapered, using shims will probably be more accurate (strip of cooking foil or whatever )

 

[Gypo Logger]

I figured if two things are the same size, they won’t fit into each other ?!

They will stretch a mile before they’ll tear an inch.
Sorry, I couldn’t resist.

 

[Vintage Engine Repairs]

They will stretch a mile before they’ll tear an inch.
Sorry, I couldn’t resist.

Lost me there mate?!

 

[Vintage Engine Repairs]

Okk guys thanks so much, I have ordered a metor piston 44mm and caber rings with wrist pin and c clips (although will replace them with OEM clips) I couldn’t justify 300 Aussi dollars for just a piston and rings. Just dads old saw so although I wanted to go OEM, i could buy a brand new ms 261 for not much more when I replace everything all said and done. Wjththat said I’d much rather use his saw. Plus they look much better hanging on the wall used and abused.

 

[frank_]

i have fitted loads of AM p + c kits tom, and have only so far only had ring issues on ts400 chopsaws (no circlip or piston or cylinder issues that i know of yet)

 

[Vintage Engine Repairs]

i have fitted loads of AM p + c kits tom, and have only so far only had ring issues on ts400 chopsaws (no circlip or piston or cylinder issues that i know of yet)

Woo thanks frank, that’s reassuring!!

 

[farmguywithasaw]

The top of a piston will be of smaller diameter than the skirt, it will expand more up there as it has more metal/ density.

And is closer to the heat source