1. Home
  2. Honda R&D Technical Review Vol.24 N...
  3. Development of BF250 Flagship Outbo...

Technical Review e-Book: Summary

Development of BF250 Flagship Outboard Motor

Article of Honda R&D Technical Review Vol.24 No.2


The BF250 large outboard motor was developed to achieve higher engine output using the first direct air intake system to be adopted for an outboard motor.
The conventional structure had the air intake inside the engine cover in order to prevent water infiltration into the engine combustion chamber. By contrast, the developed engine, which is the first in the world to incorporate a direct intake system, is formed with an intake duct that has drainage functionality inside the engine cover so that water is separated as outside air is inducted directly into the engine. This lowers the intake air temperature more than in the conventional structure and, in combination with other specification changes, it achieved 184 kW (250 HP) with a basic structure that is used in common with the current mass production model BF225. Revision of the lean burn control yielded a maximum 30% enhancement of fuel consumption in cruising speed range relative to outboard motors of the same class. In other respects, adoption of a high durability gear case at the top of its class, adjustable idle charge system, and shifting load reduction control system heightened both durability and convenience.
In order to accentuate the appeal of the BF250, a power intake form that achieves a high level balance of functionality and design was adopted. This raises the outboard motor to the level of a finished product well suited to be Honda’s flagship model.


(1) Tsunoda, M., Furuya, K., Ohsumi, M., Shidara, S., Yonezawa, M., Kimata, R.: Development of Honda Flagship Outboard Motor “BF225/200”, Honda R&D Technical Review, Vol. 14, No. 1, p. 11-20
(2) DIRECTIVE 2003/44/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 16 June 2003: ANNEX. I. C. 1 Noise emission levels
(3) Tanaka, M., Shimizu, N., Yamamoto, H., Sakata, S., Yasuda, K., Yamagishi, M.: Development of Midrange Outboard Motor BF60 with Equipment for User Comfort, Honda R&D Technical Review, Vol. 23, No. 2, p. 22-29

Author (organization or company)

Yoshihiro HARADA(Power Products R&D Center)、Kazuhiro ISHIZAKA(Power Products R&D Center)、Go TANAKA(Power Products R&D Center)、Kunihiko ISHIZUKA(Power Products R&D Center)、Fumiya ISONO(Power Products R&D Center)

We would like to get your opinion on this research paper. (This is only applicable to registered members.)

The readers of this research paper have also selected these research papers.

Development of Gear Case for Large Outboard Motor
Article of Honda R&D Technical Review Vol.25 No.1
Development of Honda Flagship Outboard Motor “BF225/200”
Article of Honda R&D Technical Review Vol.14 No.1
CFD Calculation of Cavitation in Outboard Motors
Article of Honda R&D Technical Review Vol.30 No.2