Anyone ever seen a cylinder do this??

[S&S_Work_Saws]

Pulled a stihl 460 apart this evening that's been laying in my parts pile forever. Figured I'd use it as my next project. I got the cylinder off of it and noticed a very strange wear pattern. I've never seen anything quit like this. It doesn't seem to be isolated to one area either. It's the same throughout the entire cylinder.

Any ideas what could have caused it??

 

[Yukon Stihl]

Is it an OEM cylinder?
Looks like someone cleaned transfer off with an stone

 

[jacob j.]

Looks aftermarket to me. Some of the aftermarket jugs have a weird finish on the plating.

 

[drf256]

Which part or the “Strange” are we talking about?

The circumferential lack of plating at the bottom of the bore is nothing I’ve ever seen in an oem jug. Unless it’s an optical illusion, that had to be done by someone after the factory.

It really does look like someone used some type of abrasive on the bore. The really thin AM plating kinda gets a zebra-ish look to it when it starts to wear.

I’d really like to know if it’s OEM or AM.

 

[bogieboy]

Going out on a limb here but that looks aftermarket to me, grain size and color of the casting, coupled with the lack of plating to the bottom of the bore...

 

[Gord]

Looks like someone got a little agrssive removing transfer.

 

[beaglebriar]

Looks like an opportunity to experiment. Slap a cheap piston in it and run er til she pops.

 

[S&S_Work_Saws]

It is definitely an AM cylinder. I think I got this particular saw with no fuel tank on it and couldn't figure out why they tore it apart in the first place. The spots are nothing like I've seen before. You can't feel them at all and it seemed to still have plenty of compression. There is no scoring and the piston is Clean.

 

[huskihl]

High spots or out of round cylinder. Or piston is too tight.

@drf256 had it happen in an AM cylinder awhile back

 

[legdelimber]

Almost like the cylinder has/had a little bit of warp/distortion and someone re-chucked it and ran a tool post grinder up in it.

 

[Chainmale]

Looks like it's had a pretty hard hone of some sort

 

[drf256]

High spots or out of round cylinder. Or piston is too tight.

@drf256 had it happen in an AM cylinder awhile back

yup. That odd mottled/zebra like pattern.

 

[wcorey]

Plated over tooling/chatter marks...

 

[Stump Shot]

Plated over tooling/chatter marks...

Bingo!

 

[popopboat]

Chineseum engineering for optimal oil retention !

Have a cheap aftermarket cylinder that looks like this, athough not as severe.