I have seen tons of boat builds up here but no motor builds so I figured I would do a outboard rebuild for the little sceptre up here if any body has interest in seeing it done. Nothing wild like the race boat will have but a basic rebuild and hop up on a common 2 stroke outboard. With the racing season over I made some time to get my new motor for the sceptre put together. I started out with a 2001 Mercury 200 efi 2.5 outboard (2.5 is the best and most popular block mercury ever made) that had a new 2017 power head installed on it. The power head suppose to have around an 100 hours on it and be like new but I decided to pull it apart and add new rings just so it would be a fresh new motor once it went on the boat. Once apart it looked like new, I was questioning myself for even opening it up. We now that it was apart, I decided to do the rings anyway just because at this point why not start the hour counter over again. The bores all looked good but I took it to Tommy Dunn of Get it dunn racing just to have him to check the tolerances. Tommy is one of the best racing mercury mechanics on the east coast. He builds big power outboards for the drag racers that are all over the us and other parts of the world. Any way, he checked it and told me I took apart a perfectly good motor for no reason but at least now I know what I got. He did do a slight hone to give it some better oiling hone marks to keep the pistons lubed better. The block got some rod slots to help direct the fuel mixture to the ports better for a little more power and a few other little tricks to hop it up slightly. While he had it I let him check the crank and add new high performance metal caged rod bearings instead of the factor plastic mercury ones. Polished up the crank journals and assembled the rotating assembly after he spent 3 hours cleaning the block. They are meticulous about cleaning the blocks and keeping them clean. The 2.5 blocks they build turn over 10,500 rpms and make 350 plus horse power. Mine will stay under 6200 and make 225-230ish so no near as much but still good to keep it clean a possible. Once back to the house I got the block and set up on the work bench and started putting it back together. I started with the exhaust divider, gasket and bolting it on while checking toque specks. I use the factory Mercury manual to aide in assemble due to it is 100x better than the aftermarket type service manuals. They run $100 but you can find them on ebay for $20 buck or so normally. Next I installed the heads, Got the surfaces prepped well then added the gasket and installed. Factory heads get installed with yield to torque bolts so you are suppose to torque to like 30 lbs then 1/4 turn to stretch the bolts. If you reuse the bolts you need to install them at just standard 40 lbs and no extra turns due to the bolts are already stretched and will not need the extra turn. If you do the extra turn, it will likely strip out the aluminum threads due to it ends up tighter cause the bolt has no give after pre-stretched. Next I try to get the reeds and adapter plate on so that it will close off the block and keep any dust out. The reeds I use normally are carbon or an epoxy/glass type. If you suck one in the motor if it breaks it will not hurt much. The factory ones are metal and will tear up a bunch of stuff it one fails. The reed cages I am using are plastic coated aluminum. The plastic coating will help them seat better for less blow back and that means more power! All that gets torqued to the correct speck then its on to the popet valve. The popet gets new gaskets, a new diaphragm, spring and block bushing/seat. These things leak all the time and get a little tear in the diaphragm and start dripping out the weep hole. If not fixed it will fill up the lower cowl with water and possibly suck some in the motor. I had my son help me with the torque on it. Some Pics of the rebuild:
Service Manual:
Block/Rotating assembly:
Port side:
Cylinder Hone:
O-ring Head:
Exhaust port & new Rings:
Exhaust divider in:
Keep it clean!
Reeds:
Popet Valve:
