Re: Mercury 650 problems – is it worth an overhaul?

[shoestringmariner]

quote Seakaye12:

Yes the primer bulb needs to firm up and stay firm. If it’s soft….then fuel is leaking somewhere. If it hasn’t already been checked; add the fuel pump to your list of things to check for fuel leaks in addition to flooding carburetors. The fuel pump diaphragm might be leaking; allowing fuel to flow into the intake port.
I have a 1977 Mercury 850 and when I got it nearly 10 years ago the wiring was so bad that I wouldn’t dare hook a battery up to it. Ready made harnesses are most likely still available; otherwise just replace one wire at a time. Hopefully you don’t have issues with the wires running up under the flywheel to the stator and trigger. Those were bad on mine and I ended up replacing those components. In the long run it was OK because the CDI brand replacement ignition components are said to be better than the original Mercury parts. Modern electronics of course.

Multiple carburetor engines really need to be maintained (the carbs) because if one goes lean from getting partially plugged it may not be all that noticeable but can cause lean running and melted pistons.

If you feel it might be over-revving I would take it easy until you get a tach. They are not that expensive and would make a great addition to your instrumentation.

Thanks for your input. I mentioned that I was planning on rewiring it over the winter. He said that I had to use the exact same gauge and length of wire had to be identical as the wiring in this system is resistance sensitive.

As for the tach, a sticker under the hood said to make sure the tach was “quicksilver compatible”. Truth or fiction?

Also,I was told the top and bottom carb are different sizes because one carb feeds one cyl and the larger one feeds 2 cylinders. This is the strangest thing I have ever heard.

Lastly, do you know where I might find replacement harnesses or someone who makes them?