066 scored piston

[timberturner]

hey gang,

wondering if y'all might be able to give me some idea as to what causes a "scored piston" on a stihl 066 ?

thanks

 

[treeclimber165]

Not enough lubrication. Either too lean of a carb setting or too lean of a 2-cycle mix (or straight gas).

 

[z4lunch]

Steve here... Is it scored on the intake or exhaust side. In take side can mean a cold seeze.

 

[timberturner]

exhaust side scoring

i bought this saw used so i can't speak for the previous use, but when i was running it, i had 50:1 mix and that's what's recommended

would heavy milling cause this to happen ?

 

[tundraotto]

bad airfilter, airleak, lean carb setting, overheating, bad or not enough oil....you're going to have to find out where the piston is scored like z4lucnh said to try narrow it down. often after the problem is cured you can throw in a new piston and rings and your good to go

 

[bwalker]

A seizure on the intake side usually means it was ran without oil, a cold seizure will be all the way around the piston, and a lean seizure will usually be on the exhaust side.