Re: Engine size?
Very expensive, converted my 2000 40 HP 3 cylinder Mercury to 50 HP and it cost me $375.00 for three new carbs, new oil pump and bigger tee fitting for oil injection system. and replaced reed stops with Boysen reeds(another hundred bucks..). I did sell the carbs and oil pump to recoup some money. Got 150.00 for all the ole parts. They only had about 75 hours on them in fresh water only. The only reason I did this is because I got this engine brand new for $2,500.00 bucks from Bass Pro. This is the only difference on the 40 and 50 hp Merc's. The 60 HP block is identicle BUT DOES have port work and bigger carbs yet. This upgrading of engines to next HP has been covered many times on this board. There ARE a few engines that can be converted, BUT about 95% cannot without spending huge somes of money. Late Merc 20 to 25 is carb only. Force/Sears 7.5 to 15 complete induction manifold and carb only, most Force/Sears 9.9 to 15 is carb only. And some EARLY JohnRude 9.9 to 15 HP carb only. Boysen reeds are probably the best thing you can do for your outboard. Before reeds I turned 4,900 rpm on a good day with the 16" pitch prop on my boat(a bit low) With reeds I get a consistant 5,200 RPM. Hole shots are better and idle is way smoother. This was BEFORE 50 Hp conversion. Went from average 37.3-6 MPH to 39 MPH GPS with reed conversion only. With the 50 HP conversion the boat now does 44-45 MPH with a 19" pitch prop. Keep in mind my boat only weighs 650 lbs all up weight plus me at 235 lbs to get these speeds...
