Pinching piston to correct piston slap

[Woodslasher]

Maybe just get a new saw. You don't have to fret then

But still put a new piston in this one and keep it as a backup, just 'cause. Then get a parts unit or three, build a 2nd junkyard dog out of them, realize you still need a few parts saws, etc, etc, etc,

 

[davidwyby]

@Stump Shot I dig it.

My concern was the knurling process folding the skirt inward with nothing to back it up like a knurling machine.

 

[davidwyby]

Edited OP for clarity. It kinda reads like I pinched it .020” out of round. That’s how far I had to take it to overcome the metal memory, but I only ovaled it .002”-.003”.

 

[Stump Shot]

@Stump Shot I dig it.

My concern was the knurling process folding the skirt inward with nothing to back it up like a knurling machine.

Like a lot of machining processes, you go a little bit at a time. The old timer that taught me had done lots of them and never had a machine, just a lathe and put on everything from the common rebuild to the race track.
Plus if I can do it, anyone can.

 

[davidwyby]

It was a bout .007” smaller on the corners of the skirts. I put a meteor in, play with this another day.

 

[Woodpecker]

It was a bout .007” smaller on the corners of the skirts. I put a meteor in, play with this another day.
View attachment 355905

Quiter

 

[Al Smith]

Back in the days of the model A Ford knurling was a common practice .I can't honestly say as I've ever seen it practiced on a 2 cycle engine .That said as a rule on any piston it will have ovality and usually the skirt will be wider at right angles to the piston pin .That plus it will have taper from the skirt to right below the rings .If the knurling expanded too much metal it would be a good trick on a standard engine lathe to cut it back down to size .

 

[srcarr52]

It was a bout .007” smaller on the corners of the skirts. I put a meteor in, play with this another day.
View attachment 355905

Yes, that is why they are shaving the bottom of the intake skirt off.

 

[Al Smith]

There is another process that also might go back to the model A ford ,piston peening .Which somewhat like knurling would just displace the metal a little bit .My brother has the device which is some what like an air chisel with a captive ball bearing .I've never seen it in practice .