Merc 2.4 Motor Mods


It's great to have such a knowledgeable resource and addition to the already wonderful I.H.R.  I entered the world of performance boating the summer of 2000 with a purchase of a 1990 Vegas XT.  The motor is a stock 1990 Merc 200 Black Max with 6" set back, and it's turning a 14-1/4 x 27 Mazco.  Coincidently, I store the boat in Richmond, MN, and I sometimes frequent the Sauk River.

The original power head blew in 1994 and was replaced with a new power head (#813043A89) that same year. First, based on the part number, can you tell me if there are any notable differences between the newer power head and the one it replaced?  Second, I would like to start having some minor motor modifications done.  What types of beginner mods would you suggest a guy like me start with?

Ryan Hallesy
Plymouth, MN



If your boat is white with blues and a black tail, I know the boat. Your new powerhead is basically the same with some piston and rod updates. First thing would be make sure it has solid mounts. That motor likes a little more compression. A set of Boyesen reeds of the rubber coated type should be on the shopping list. I'd get rid of all the advance/retard modules and run 25 degrees of timing. Chucking the oil injection would be wise if you can live without it. I'd pull the liner and change the pipe to a 41941 exhaust tuner. I'd leave the center stock and not drill the exhaust relief holes as they just make noise and no power gain. You would kind of end up with a homemade promax. On a Vegas that should get you past 80. Drop by sometime if you want. We have a hotboat club that has a few rallies on Gull and Whitefish lakes. It would be great to see you there. Mostly just general boating and relaxing fun with up to 45 other boaters. Sometimes I bring a bunch of props to try for people to experiment.

Hope this helps and hope to see you.



Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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