STIHL Stihl 044 piston top pitting

[cshunter83]

I just recently put an OEM Stihl piston in an 044 due to the wrist pin bearing failing and scoring the piston. Just for kicks I pulled the muffler after some use to take a look at the piston and it appears the top around the edge is pitted and rough to the touch. What would cause that?


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[Pincher]

the one piece of the old needle you didn't find? lol. Add picture if possible. Everyone like pictures.

 

[drf256]

Detonation

 

[cshunter83]

the one piece of the old needle you didn't find? lol. Add picture if possible. Everyone like pictures.

I’ll try to take one but I don’t know how well you’ll be able to see it since it’s still in the cylinder.


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[drf256]

If you have not pulled the jug, the top will not be truly readable. All sorts of visual distortions can occur when trying to view the cylinder and piston without disassembly.

You could simply be feeling carbon on the crown.

 

[av8or3]

I once “holed” two pistons on a Yamaha rd350 after paying for after buying and riding off happily on my way. First one cyl quit and then the other. There were little round balls of aluminum packed around the ceramic insulator for the spark plug The dude that sold me the bike changed the plugs “as a favor “ to me before I arrived to pick it up. He put lawnmower plugs in it. Waaaay too hot of a plug and it caused detonation that melted the top of the piston. True story. Was an easy and not too expensive fix but I learned the importance of heat range.