Rust on pistion

[Justin Taylor]

Ok so i rebuild a ms 311 with a used pistion cylinder and i cleaned all of the carbon off and had it runing for a bit then let it sit for a week and went to go do a compression test and theres like a lot of carbon and what seems to be rust or orange somthing what could this be?

 

[Leerod83]

Can you put some pictures up? Could it be dirko? If that's what you used to seal it up. Is the 311 still a clamshell? I've never had one apart.