I am looking at a Mercury 6HP motor as a possible purchase. I plan to run it on my boat soon to decide if I want it. Initially what I have done is run it in a barrel. It runs pretty smoothly after the initial coughing (the motor sat unused for 2 years). I drained the lower unit and replaced it. The oil looked pretty dark but I found no particles in it and I did not notice any water. I noticed a couple of things I wanted to check into before putting it on the water. I know that a motor will smoke quite a bit more in a barrel than on the water and this one is smoking pretty good and particularly at higher throttle. The plugs seem to be staying pretty clean and they were on initial inspection. Are there any checks that I should do to the carburetor or anything else prior to putting it to the test? I used a 50:1 mixture. Is this correct? I apologize but I did not get the model number on the motor. I believe it is a 60's model. I will get the serial number today and post if that helps to know for sure. Also, the water flow from it is rather low. It barely trickles on idle and picks up some on faster speeds but not where it whould be. I noticed that there is a plug on the underside of the top section of the motor up by where the pee hole is located. This plug comes out with a regular screwdriver and is labeled "Fresh Water Flush". I figured that this is for cleaning the water pump area out? When I pulled the plug and looked up in it, it appeared to be completely clogged with what looked like hardened water. Should this port be clean? And if so what is the best way to do so? Thanks in advance!