The manual I have says .060, but others say .035-.040, so I am not sure.
The dry weight of a 1988 model, 115 hp Mercury outboard is 312 lbs.
The spark plugs on a 1988 model, 70hp Johnson outboard, should be gapped to .030in.
The 4 stroke Yamaha outboard requires a quality SAE 10W-40 motor oil.
The listed dry weight for a 1988 model, 70 hp Mercury outboard is 265 lbs.
The dry weight for a 1988 model, 20 hp Mercury outboard is 105 lbs.
The serial number, or the year model is also needed to answer this question. The 70hp engine underwent a major redesign, resulting in a significant weight difference.
A 9.9 hp Mercury outboard, serial number OB235459 is a 1988 model.
dry weight is 188lbs.
108 lbs.
A 25 hp Mercury, serial number OB283551, is a 1988 year model outboard.
A 20 hp Mercury outboard, serial number OB268004 would be a 1988 model.
A 15 hp Mercury outboard, serial number OB31814B, would be a 1988 year model.