I have a 1988 Mercury Classic 50 (45 hp) 4 cylinder outboard and I have just
bought the Mercury Shop Manual for this unit. The manual is quite good but
as I am new to outboard mtc. I have a hew questions for the experts:

1. In my sailing days I had a 6hp Johnson which had a thermostat but I
cannot find where this is located on the Mercury. Does anyone know if this
unit has one and where it is located.

2. I would like to check the compression but am concerned about damaging the
electronics. Is it required to disable the spark, if so how. Manual does not
say.

3. How does one adjust the linkage between the upper/lower carb to be sure
they open in sync. Once again manual does not say.

4. How would I connect a tach and temp sensor. Is it possible? The local
marine store has a box full of used tachs and I would like to put one in if
practical.

5. The engine runs rough but a quick pull off of the top carb indicated
improper float setting causing overflow on to bottom carb. I quickly did a
tweak and overflow has stopped but it idles rough so I assume I need to pull
off fuel system, clean, adjust and re-try. Any suggestions, tips would be
appreciated.

Any other advice would be appreciated. I know some do not seem to be Merc
fans but I admit I like the look and it seems just to need some tinkering. A
little like an MG, Triumph or other British sports car.

1: No thermostat
2:What kind of control box do you have.. A Merc box should have a Lanyard
(kill) switch. Tho no damge will come from not disabling the spark when
checking compression, that spark is strong, and stray spark is not good if
there are fumes etc.
You could easily do a compression test with the ignition off by using a jumper
and bypassing the starter solenoid.
3:The carbs have a non adjustable link between them. It's a slot arrangement
4: Tach is easy depending on the type of control box. Merc boxes have a tach
plug in.
If it's a binnacle box you willl need to wire it into the ignition harness.
There really was not a good temp guage for that motor. Better to get a water
pressure guage.
5:That engine had been around for MANY MANY years. It had a great reputation
and still has many fans today. A lot of people liked its smoothness, especially
at idle.
In my opinion the carbs are finnicky. Tough to R&R too. If I recall the starter
has to come off. The carbs themselves are simple.
Many people were sad to see that engine go away. It was a expensive motor for
them to build. It also was a crossflow, and not as fuel efficient as newer
motors.
Do yourself a favor and go through the carbs.Make sure they are clean. When you
adjust the mixture, do it on a warm engine, running at idle In gear.
And oh yea, I had a few myself......