can you sand a piston?

[oaky]

can you? or will it rock

 

[Dub11]

What end are you sanding?

 

[jacob j.]

I'm guessing you mean sanding the skirts? typically, by the time you've sanded out the damage from a "burnt" piston, it'll be too loose in the bore (in a modern saw).

 

[Stump Shot]

About the only way I know how to "get away" with doing this and have success is to knurl it afterwards and then hand fit it to the bore. New pistons can generally be had for cheap and are not worth this trouble unless it's some kind of antique last one in the world type scenario.

 

[CR888]

can you? or will it rock

Why do you want to sand a piston, what's the problem with it? Crown or skirt you need to sand?

 

[ManiacalMark]

You can sand the crown to polish it if you want but I wouldn't go sanding the skirts.

 

[Al Smith]

Knurling a piston might have worked on a model A Ford but would not be a good idea on a chainsaw piston .You can buff a nick out of a piston if it isn't too deep .
Some time ago one John Lambert ,AKA Gypo Logger ,Franks Planks ,Yukon John and a number of other handles bought a brand new Stihl 044 and began a most comical story of porting the thing using a chain file and sand paper over the course of a winter .Due to a number of mis calculations and mistakes he managed to hang that thing at least two times . Sandpaper and flat files he got it running again .I ran the thing as did others and believe it or not it did very well even with half the parts like the cover and air filter missing .

 

[Stump Shot]

 

[Deets066]

View attachment 163295

That would work, but I wonder for how long?

 

[oaky]

something fell through the intake or exhaust port on my stihl 076.
marked up the piston and cylinder. i sanded the piston without thinking..
it looks perfect ha but i guess it wont work. cant find pistons on their own.

stemmed from buying a brand oem new "ts760" cylinder piston kit, prepped the saw for a rebuild ended but being a ts510 kit. so i started looking at my old cylinder and piston.

the cylinder will clean up well for resale. the piston was pretty much new so i thought id sand

 

[oaky]

 

[oaky]

yep

 

[grizz55chev]

View attachment 163323 View attachment 163324 View attachment 163325 View attachment 163326 View attachment 163327 yep

Did you check skirt clearances after the sanding?

 

[Stump Shot]

That would work, but I wonder for how long?

According to the old fart that showed me how to do it, life expectancy is actually increased, he also stated that not as much in two strokes vs four stroke engines, citing increased oil retention also it lessens the chances for galling or seizing, but does not eliminate it. Heat transfer is still happening enough to allow everything to work as intended.
I couldn't say personally as a play saw doesn't get used no where near enough to get any kind of data from good or bad. That said, I would have no problem doing this with an antique power saw if no other options of replacement were available. So in that sense, it won't last at all in the garbage can, so any use at all would be in the plus category.

 

[Stump Shot]

That would work, but I wonder for how long?

 

[Stump Shot]

And for the record, Model A Ford pistons are not a good candidate for knurling as the were of a hard/brittle type alloy.

 

[Stump Shot]

View attachment 163323 View attachment 163324 View attachment 163325 View attachment 163326 View attachment 163327 yep

That piston looks okay in your picture, you would have to check how it fits in the bore still. If you can put it in the cylinder with the plug hole blocked off and let it go and it floats down that's a good sign, if it drops like a rock, not so good. Then it would have to be ascertained that there wasn't excessive room on the skirts. compare this in the bore to a good spot on the piston at the crown to see of any differences.
Otherwise it's really hard for anyone here to say not knowing exactly what you did there. Check it out and go with your best judgment after that is best I can say.

 

[Stump Shot]

Normally I say it's just a piston, smoke'em, if you got 'em and I will put a new one in. Knurling is a kind of a last resort fix, or as a hot rodding trick for less friction. I think of it as old school Teflon coating.

 

[oaky]

seal the ports best i could for now.

 

[grizz55chev]

seal the ports best i could for now.

There’s an acceptable tolerance, not sure of the specifics but that one looks a little loose. Check it with a feeler guage, off the top of my head I think it’s around .003”, but don’t quote me.