Huzza! Thank you Charles. Outboard motor specifications

[Norm L.]

These are from the US distributors as they were provided. I'm sorry my "format" didn't hold up to the transfer. I don't know if Yamaha stopped making engines under 15 HP

SMALL OUTBOARD ENGINE SPECS to 15HP
BRAND   MODEL      WEIGHT   HP/RPM      CU INCHES

               
Evinrude   E3RD4      41      3.5@5000      87
      E6RG4      55      6.0         123
      E6RGL      57      6.0         123
      E10RG4      81.5      9.9         209
      E10RGL4      103.6      9.9         209
      E10TPL4      103.6      9.9         209

NOTES 
All outboards are generally rated at 5000 RPM give or take 500.
The difference in weight of same HP engines is probably due to length.
The number 4 indicates 4 stroke engines.
Some manufactures, like Honda, didn't sub list engines with same HP but slight variations in weight.
Large jump in weight is moving from one cylinder to two-cylinder engine.

Honda   BF2.3         30      2.3         3.5
      BF5         60      5.0         7.8
      BF8         107      8.0         13.5
      BF9.9         92-107   9.9         13.5
      BF15         105-115   9.9         21.4

Mercury   5 Sail Power   59      5.0         7.5
      5 Propane      59      5.0         7.5
      6         57      6.0         7.5
      8         84      8.0         12.8
      9.9         84      9.9         12.8
      15 EFI      99      15.0         20.3

Suzuki   DF6A         55      6.0         8.9
      9.9BF         98      9.9         20.0
      9.9BT    EFI      120      9.9         2.0   

Tomatsu   MFS2.5      41      2.5         5.2
      MFS3.5      41      3.5         5.2
      MFS4         57      4.0         7.5
      MFS5LPG      60      5.0         7.5
      MFS5         55      5.0         7.5
      MFS6         55      6.0         7.5
      MFS8         82      8.0         12.8
      MFS9.9      95      9.9         20.3
      MFS15      95      15.0         20.3

Torqueedo   3.0R         ?      3000W/6 HP
      3.0T         ?      3000W/6 HP
      6.0R         ?      6000W/9.9 HP
      6.0T         ?      6000W/9.9 HP

Yamaha   F15         111-132   15.0         22.1               

[Frank B.]

Interesting.  Difference in weight can also be function of Electric start or not.  You can also tell from the chart if you can raise the HP on the motor by noting the same displacement for multiple HP motors.  On the four strokes it is normally just change the carb which is what I did on my Suzuki 9.9 to change it to 15.  It made no difference when it was on the sailboat with the flat pitch prop, displacement hull speed and all, but when I put it on the planing skiff with an appropriate pitch prop to stay in the RPM range, the extra HP was welcome. I actually went down in HP to a 6hp for the sailboat to drop forty-five lbs. of weight on that moment arm mount and the sailboat was much happier.

I wonder if you can change the HP on the EFI models.

[Norm L.]

Frank, thank you for pointing that out. I noticed that and how the manufacturers played with one set of cubes. I thought that would be helpful for some in choosing an engine that they might want to modify.
There is also the factor that HP is one point but one must consider the boat's hull shape and weight and the correct prop.