Stihl 260 Scored Piston Pics

[bradgil]

Here's the pics from my Stihl 260 that had the ticking/knocking noise at idle. Seemed to run and cut good, just made a noise I didn't like. Compression warm was 85 lbs.

The jug has some marks but you can not feel them other that two small specs of aluminum embedded on the exhaust side.

The piston has two scores on the exhaust side and one score on the intake side. Rings looked fine and were not stuck.

Can this scoring cause the noise that I was having??

I'm looking to just order an aftermarket piston kit from Baileys to get this saw going again.
What can I do to clean up the jug a little, or just leave it alone??

Just looking for advise on where I should go from here.

Here's the pics (click to enlarge)

Jug Exhaust side


Jug Intake side


Piston Exhaust side


Piston Intake side

 

[Cut4fun]

Yep reminds me of my first great ebay saw purchase. Poulan Badboy 3750 60cc runs perfect, no problems, ready to cut, great compression. Well got it and it would barely cut. Turned out to look just like your 026. I reused the piston and cylinder after alittle clean up work. Got new ring and new base gasket and havent looked back. Thats how I got hooked into all this chainsaw stuff. Just wanted to keep learning after that. I fixed mine looking just like your scoring job for a total of $16. Half of that was shipping cost too. Good luck on the fix.
After looking at your piston, mine wasnt gouged that much.

 

[NWCS]

use a good hone and lots of light oil on the hone. or have a shop do it that has a hone. you want to get the entire cylinder crosshatched anyway to seat the new rings.

 

[Gypo Logger]

Just to show how tough the chrome on those cylinders is, you could sit there with a an emery wheel or scotchbrite till hell froze over and you wouldn't damage the cylinder. My point is, chrome or nicosil is not fragile material and almost impossible to damage save for ingested abrasive material or a broken ring. Even a lean seizure simply deposits some piston material on the barrel which is nothing you can't buff out.
Just like Cut4Fun said, clean things up and put in new rings and you won't look back.
You have nothing to lose.

John

 

[bradgil]

What about the rattling noise that I was hearing. Could that amount of scoring cause the noise???

If you look at the bottom of the piston, the skirt on the intake side is a little thinner than the skirt on the exhaust side. Would that be normal, or the cause of the piston slap????

Thanks again for the help.

-Brad

 

[Lakeside53]

What about the rattling noise that I was hearing. Could that amount of scoring cause the noise???

If you look at the bottom of the piston, the skirt on the intake side is a little thinner than the skirt on the exhaust side. Would that be normal, or the cause of the piston slap????

Thanks again for the help.

-Brad

Yes, your skirt is worn. Don't mess around - hone the bore and just put in a new piston. Then it's good for another 1000 hours. I see this all the time in 026/024 that have had bad filters where the flock has been scrapped off by over zealous cleaning. Yours looks more like lean seize though than just air filter issues. If you use the same piston it will slap just like before and your idle will never be stable.

Now for the kicker - is your piston 44mm or 44.7???? Aftermarket piston are only 44mm... serial numbers after 262 187 361 are 44.7.