Hi, I've recently taken off the cylinder head on my old CBF250 (spark plug thread stripped and needed helicoiled). Left the bike outside, came back after a week and the tarp had blown off.
There was a small pool of water sitting on the piston head (which is more or less at BDC), and also rusty orange patches all over the inside of the cylinder wall above the piston (thinking the Nikasil must have oxidised?).
I've dried off the water on the surface (though who knows if any has slipped down to the O-rings or past them) , and the orange deposit seems to wipe off OK.
Wondering whether it's OK to go ahead and rebuild the engine from here, hoping it'll work OK with an oil change and blow out any water left in? Or should I take off the engine block and do anything more drastic (re-coating the cylinder walls, replacing the O-rings, etc...)
So muppet here would really appreciate any advice as this seems like it could be an expensive and time-consuming job, but don't want to half-ass it either
Thanks in advance!