there's a book available called "Hollywell Interchange Book" and it will tell you everything you need to know
you need to get a rebuild kit which comes with new gaskets jets and maybe floats. depending on what you mean by fixing.
I
These motors will go to about 140 000 before needing any rebuild.
The horsepower of a 1985 Ninja 600 is 75 Max
approx 3500$ canadian in 1985
Street.
.7mm
.7mm
in the back of a service manuel
70 horse 1985 mercury outboard
underneath the rear fender.