I have a 2016 Mercury 115 four stroke. I changed the prop with the same one that was on it, Spitfire 13 x 17 and installed new bore sleeve. Right after getting on plane something happened. Hard to explain but might of been cavitation. Was like it was spinning freely. Shut it down and looked at prop. Tried again and same thing. After that it worked fine. I am at a loss? Might be just me but it seems motor louder now.