Yes. Rough idling can be attributed to many different factors including carburetor jet settings, bad fuel, dirty fuel system, fouled plugs, bad timing, weak spark, high altitude,low cylinder compression, worn rings, poor electrical connections, carbon trail on magneto cap, or even to low of an idle setting.
The plug gap for a 9.9hp Mercury outboard, ( all models ), is .035 - .040in.
all mercury outboards mix 50:1
no it is all in how you take care of it
Two items are needed to determine the year model of a Mercury outboard, the serial number and the horsepower rating. From the information given above, all I can determine is a pre 1985 model.
By 1971, virtually all outboard manufacturers had gone to the 50-1 mix, and Mercury prided itself on being ahead of the game, so you are safe with the 50-1.
No as all the inline 6 cylinder motors are a 2:1 ration and all the small inline 4 cylinder are 2:3:1 ratio
86 octane is all that is needed. In otherwords...regular gas!
you want at least 120 PSI on all cylinders
I should be equal on all cylenders and about 110 to 120
http://www.oldmercs.com/models2.htmThis site has almost every part for old mercurys. They are not obsolete! I just my 1977 9.8hp outboard all the time!
The horsepower rating is one of factors needed to determine the year model of a Mercury outboard. All that can be known from the serial number only is that the "OB" model Merc was manufactured during the late eighties.
This is a fairly vague question to answer, but generally all that is needed for an outboard carburetor is a good cleaning, and to install a new gasket kit. Hope this helps.