Honda 9.9/15/20

Is it possible to distinguish between the 2006 honda 9.9, 15 and 20-hp outboards without refering to the sticker on the cover? I've not been able to find a freeze plug with the hp stamped on it. I ask this because I want to run my 20-hp at a reservoir that only allows up to 10-hp motors, and i have no problem removing the sticker. These three motors are all 2-cylinder and are the same size. thanks.

 

In Norway it's quite popular to buy the 9.9HP and remove something (in the carburettor?) to make it 15HP, due to taxes. 20HP I dont know, but I would guess they are identical.

 

Yes. Honda's BF8 and BF9.9 use the same 222 cc block, the 9.9 is rated for 5500 rpm while the 8 is capped at 5000. Similarly, the BF15 and BF20 use the same 350 cc block; the 20 turns 6000 rpm while the 15 is capped to 5500. IIRC the differences are mainly in the carb although I think there's also some ignition differences. So you can make a 15 out of a 20 or vice-versa, or an 8 out of a 9.9. Turning a 20 into a 9.9 would require that you place a restrictor in the air intake or adjusting the computer to cap it at around 3500-4000 rpm, but it would still be a larger motor.

Perhaps you'd get away with it. But that doesn't make it right or legal. Those rules are there to protect that reservoir and its environment. The authorities don't want bigger, faster boats on there. My suggestion would be to check with the authorities to see if placing a restrictor plate in your BF20's air intake while on this lake would be acceptable. Intentionally disobeying waterway restrictions is illegal and immoral.