o11 muffler question

[David Y.]

My 011 is missing the muffler screen and cover. Does it damage the engine to run it without them?

 

[Bowtie]

It can damage the engine by way of the saw possibly running too lean, and by getting debris (saw chips, dirt) into the cylinder. My opinion, get the parts you need to fix it right and save the worry and despair of a damaged saw.