TOPIC: Merc 650 pre start repairs?

'64 650. My boat is finally in the stages of restoration ( well deconstruction now ) and I don't think it will take too awfully long to get the glass work done and put it back together ( not splashed this season for sure but I have tags just in case )

The 650 was put away 'not running' about 12 years ago. It turns over with 150 PSI on all 4, so it should have at least 120 across all 4 when it's alive. My grandfather who gave me the boat, had lost interest in the boat by that time and he just couldn't get it to fire Boat was bought new, and I think he said the motor was new at a later date but possibly used ( doesn't matter, it's over 40 now )... I lubricated the cylinders with TCW3 3 separate times but it has only been spun by the starter for the compression test..

I have a brand new set of points, spare magneto+ drive that I got off Ebay+ the one on the engine looks decent. Sierra Marine Water pump kit. I lack fuel lines and a fuel pump kit, but I don't know what to get as far as a pump kit because it has 2 pumps.. Few questions

1.
How do I get the cap and rotor off without busting them? I also cannot locate a cap gasket from Oldmercs. What do I do?
2. Never done a Merc water pump and my manual ( it is OEM ) was used and rebound off Ebay and appears to be a compilation of 3 different manuals and is little use.. What is the procedure?. I know the bolts to the LU, but don't know how to pull the trim tab/ annode or anything else. Found newer merc how to's but I'd assume the old girls a bit different.

3? can it be fired up without controls? It does have a rectifier and charging circuit

I have a 64 650, wish it had the kind of compression you're seeing. There are a lot of folks here that know much more than me about these motors, so I'll limit my answer to what I know for sure. The anode is held in by a large allen bolt that is accessible through the upper part of the foot. There's a hole that probably has a rubber plug in it. I don't recall the exact allen size offhand. There are five nuts and one bolt that hold the foot in place. The 5 nuts are easy to locate. The final bolt can only be accessed after you remove the anode. Before you remove the lower unit, put the shifter in forward and leave it there. Once the foot is off, don't twist the shift rod at the front, or you could have shifting difficulties after you reassemble. Also when you reassemble, it's a good idea to just start the nuts but don't pull them up. Then take a long screwdriver and, inside the motor housing, tap down lightly on the shift quadrant until it pops down onto the shift rod spline. Otherwise, if you just pull the nuts up tight, the quadrant may be pushed upwards and hit the bottom of the carb throttle rod.

I think it's possible to damage the charging circuit if you run it without a battery hooked up. My charging system hasn't worked since I got mine, I just use battery power to crank it up, then it gets its spark from the magneto.

There are some online shops that sell good manuals, pricey but real useful.

PM me if you run into any problems, I'm no expert but over the past year I've learned a lot from the folks here, and glad to share what I know.

actually you can run without the harness if you unhook 1 yellow wire from the rectifyer.if nit you will burn out the rectifyer.

Thanks. Found the yellow wires. should I disconnect both?

I got some more parts on Ebay. New OEM condensor, 2 fuel pump kits ( cheap enough I have a spare if I only need 1 ), magneto gasket and a clean set of Carbs for spares..

unhook just 1 yellow wire. and you can run without a battery without damage.

Cool, thanks.. Have one other thought/ question. If something were to happen to the powerhead, could I bolt a later 4cyl, like an 800 or an 850 up the short shaft lower unit and use the 650 magneto, flywheel and other associated parts? Basically make it an 850 disguised as a vintage 650?

Check the parts lists to see if the base gasket is the same.

The powerhead mounting bolts are different on the early ones.They used less studs. If your 4 cylinder 650 was newer it would swap. The fuel lines can be made with replacing the 1/8 in. pipe threaded fitting with barbed ones from an auto parts store and use fuel injection hose and clamps. A couple may need to use reducers on the fuel pumps. Use all brass fittings, no steel ones.
Fuel pump diaphram kits are on eBay all the time.
Also the top crankshaft seals should be replaced as the ethanol in todays fuel will make them hard and will cause a vacuum leak running the top cylinder lean. It will burn the top piston.
I sell many used serviced Mercs and replace every top crankshaft set of seals.
Too many come in with #1 piston scored from running lean.
Good luck and safe boating ahead for you.

Matches. Both use P/N Sierra 18-0378.. So now that's confirmed, it will bolt up.
Thanks

Well, My boat according to USCG current specs is rated 40hp at the prop, which would be about the 50hp crank rating that the boat carries ( found in the original brochures ) . I thought I could mess with the numbers enough that I could get 75-80hp but I can't get close. I had found a nice 850 long shaft on a junk boat but I think I will pass on it and wait until/ if something does happen to the 650 block