TOPIC: Merc 450 running issues

So I have my Merc 450 running, it will start and idle great. I can rev it up just fine when in gear when in a barrel of water. But when it's on the boat on the water it bogs.

A little back ground info, I acquired the motor being told that the water was not pumping out. I took the motor apart, removed the blockage, rebuilt the fuel pumps, new gaskets, new plugs, new water pump and jets for 5,000 ft and 28:1 gas/oil. Also I cleanup any carbon build up anywhere.

I have not rebuilt the carbs or replaced any ignition parts beyond the plugs.

I am thinking I have an issue with the points/ignition/timing advancing, just not sure.

I know I am close to having this issue solved, just so close to having it run right finally. Please any helps or suggestions would be great.

Welcome aboard Joe. We've got several folks very knowledgeable on tweaking and tuning the ole Mercs, I'm sure someone will be along shortly to assist you with that.

I think most will agree that it's an excellent idea to go ahead and at least pull the carbs apart for cleaning and inspection, better now than out on the water with a burned piston because she ran lean! Same goes for the ignition, at very least make sure she's dialed in and timed properly, etc..

Looks like you have a nice one there, definitely worth the time and trouble for a little preventive maintenance IMHO.

richen the idle screw 1/8 to 1/4 till it does not bog.