The dry weight of a 1988 model, 115 hp Mercury outboard is 312 lbs.
the 115 H.P. mercury was called the 1150.
The 1978 model, 115 hp Mercury outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
I would assume 50:1 but call the manufacturer to confirm
Set the gap at .035 in. for a 115 Mercury.
4 cylinder dates from 1989,you may have the first 2 digits wrong.
all flywheels are always (as far as I have ever seen) connected to the crankshaft.
The 6479053 was 1984 Production 90 to 115 hp 6 cylinder Thanks to mercurymarine.com for the info.
Mixture is 50:1
A 115 hp Mercury, serial number 6580904, is a 1984 year model.
Most of the larger outboards are two stroke, unless it is very new. Most 115 Mercurys are inline four cylinder, except the very first ones built in the 60's and early 70's
A 115 hp Mercury outboard, serial number OC238909, would be a 1990 year model.