Should this piston be replaced?

[Ryan625]

Hi, just looking for a second opinion on this piston. Found that this pistons machining marks appear to have been worn away and there's a large black mark which I'm guessing is the saw running too lean but any advice will be helpful. 

[Dan Maynard]

I'd say yes, but that looks well worn so maybe it should have a new piston/cylinder set rather than just piston.

[Ryan625]

38 minutes ago, Dan Maynard said:

I'd say yes, but that looks well worn so maybe it should have a new piston/cylinder set rather than just piston.

Strange thing is the cylinder looks pristine, no scoring or transfer that I've noticed. The saw did look like it'd never been maintained or cleaned at all when I got it

[woody paul]

I take it you have removed ring, 

[Ryan625]

Correct, Saw came with a new OEM ring because the previous owner said the ring had gone 

[openspaceman]

2 hours ago, Ryan625 said:

Correct, Saw came with a new OEM ring because the previous owner said the ring had gone 

Make sure you clean the carbon out of the ring lands before you put the new one on.

[Ryan625]

3 minutes ago, openspaceman said:

 

3 minutes ago, openspaceman said:

 

 

 

[adw]

That is going to have plenty of piston slap if you refit it, the carbon fouling is from poor quality oil being used, or far too much of it, so I would be fitting a new piston.

[Ryan625]

Ordered a new piston went with meteor, I'll have the choice of a new OEM ring or a caber ring. 

[spudulike]

Good. The piston can wear like that but the bore, being much harder, will often be fine and a new piston and ring will restore the compression and decent running.

The black bit on the piston looks like a bit of blow by down to piston wear but use semi or fully synthetic oil on these strato engines, the main bearings will thank you for it.

BTW, when you remove the cylinder, you should always blast the chip and oil away from near the cylinder base to stop it entering the engine. Always the best policy.