2009 Honda DN-01

Text: Ken Freund • Photography: Honda

Not a scooter and not a regular motorcycle, the groundbreaking DN-01 ("Dream New" Concept 1) demands a whole new classification - which Honda calls Crossover.

This futuristic machine combines cruiser and sportbike styling cues with a fully automatic transmission, low seat height and a very capable chassis. First shown to the public as a concept at the 2005 Tokyo Motor Show, the DN-01 was proclaimed production ready at the 2007 Show.

Engine

Designed for everyday commuting and spirited backroad riding, the DN-01 is powered by a 680cc, liquid-cooled SOHC V-twin engine with 52 degrees between the cylinders. The compact V-twin has a 10:1 compression ratio and is rated 61 horsepower at 7,500 rpm and 47.2 lb-ft of torque at 6,000 rpm at the crankshaft. Honda debuted this powerplant on the 2008 European DN-01 and the XL700V Transalp.

Honda's excellent PGM-FI fuel injection employs two 40mm throttle bodies and 12-hole injectors for complete fuel atomization. A closed-loop emission system uses an oxygen sensor and a catalyst to reduce emissions, while an auto-enrichment system eliminates the need for a choke. The bike starts instantly and provides quick throttle response and excellent drivability. Power is sufficient for everyday riding and highway touring, but it's not stunningly quick. There's very little vibration, and at speed it's so smooth and quiet it almost seems like an electric vehicle.

Transmission

What really sets the DN-01 apart is its hydro-mechanical automatic drive, dubbed the HFT (Human Friendly Transmission). Honda reports that current design constraints dictate that engines larger than 700cc require a transmission physically larger and heavier than a comparable manual transmission. Hence, a 680cc V-twin was designed to work with the HFT and the bike was basically built around the transmission.

Not to be confused with conventional belt-converter systems used in scooters or semi-automatic transmissions (which manually shift between conventional gears without a manual clutch), the HFT uses engine power to drive a fixed-angle swash plate to convert power from the rotating motion into reciprocating motion inside the hydraulic pump. The swash plate strokes pistons arranged in a circle in the cylinder body, causing them to pressurize the hydraulic fluid. This pressurized fluid is routed by a timed distributor valve to a second set of pistons located in the hydraulic motor, and these motor-side pistons push against another swash plate, the angle of which can be varied to provide changes in "ratio". A lockup mechanism is used to reduce power loss and improve efficiency, and a starter clutch provides a neutral for easy start and stop operation.

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For the complete article of the riding impression(s) and technical specifications, please purchase the September/October 2009 back issue.