Stihl 026 query - purchased 2nd hand

[stihltech]

Shiny piston= worn piston. Should have lines running across piston.

 

[macmurdo]

Ok I see what you’re saying
Had another look
Can see the horizontal lines on the left side of the piston but it’s smoother and even slight vertical lines on the right side, obviously wear.

What’s the advice … start with rings?

 

[flatsfisher]

Ok I see what you’re saying
Had another look
Can see the horizontal lines on the left side of the piston but it’s smoother and even slight vertical lines on the right side, obviously wear.

What’s the advice … start with rings?

doesn't look good, but kinda blurry.

 

[ZeroJunk]

That's not really wear. The tooling marks on the left are pristine.

Either too lean or straight gas in that saw's history.

 

[macmurdo]

I know it’s not everything, but compression tested about 188psi.

Is it even worth doing the rings?
Haven’t even had a chance to fire this thing up yet.

 

[flatsfisher]

you need to find out what damaged the piston and fix that. if it was straight gas, that's easy. but it could be an air leak. also, the cylinder may well be damaged also. first thing to do is a vacuum and pressure test. there are various threads on here detailing how to do that. you will need a mitey vac or something comparable. you need to do both tests. after that's done, remove the cylinder and get a look at the damage. you can also check the crank and rod bearings for wear or damage at that time.

 

[flatsfisher]

in the photo, it looks like someone may have cleaned some of the carbon deposits out of the exhaust port but just got the stuff close to the piston and left the rest of it. if you take the cylinder off, and it turns out to be re-usable, clean the rest of that out.