Mercury Boating - Popular Questions, Answers, Tips & Manuals
How do I tune a carberator on a 7.5hp mercury outboard
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.
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Trying to find the compression on Mercury Bigfoot 60 hP outboard motor
When checking the compression on an outboard motor... you aren't looking for the final number as much as the percentages of variation. There are so many things that can vary the compression numbers, like throttle position, air temperature, and even the tilt of the motor on a four stroke, that the manufacturers don't put the numbers out. What you are looking for is less than 10% variation between all cylinders. So if 3 cylinders are giving you 120 psi and the forth cylinder is giving you 105 psi, that hole has a problem. In the old 2 stroke days what we would find is people were using air cooled 2 stoke oil, which has a much higher burn temperature, and fouling the piston rings with tar.
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My mercury serial no is 8065967, what year is that please
Only things I could find ...
- S/N beginning with 8075603 , 2.2 Hp was 1984
- There was a different reference that different countries could have different serial number series which complicates matters.
- But there was also a reference indicating for outboard motors ... that the nameplate which has the model and serial number ALSO had the year written down ... the last 2 digits of the year in a box in the lower right hand corner
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