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The maker points on the 4.5 hp Mercury outboard, are set at 0.020 in.
The plug gap for the 1990 model, 100 hp Mercury outboard is .040 in.
5EA
In order to answer this question, the year model of the 90 hp in question, would be required. The range for 2 stroke, 90 Merc's is 265 - 305 lbs., depending on the particular model.
An 8 hp Mercury outboard, serial number OD140284 would be a 1992 model.
A 90 hp Mercury, serial number 4849632, is a 1978 year model outboard.
The serial # would appear to be post 1986 according to Seloc Merc outboard manual I have.
i have a 7.5 merc outboard ser.no.7678203 what jear is it vern o.
The correct spark plug gap for the 1982 model, 9.8 hp Mercury outboard is .040 in.
Say 2 Hail Mary's and repent your sins. Pray that you haven't damaged the motor and don't do it again. If it seems to be doing OK, you got lucky.
Merc's use a 50:1 mix
The points gap on a Merc 40 4hp is .020