You can't fault Triumph for trying the "conventional" route with its three previous middleweight sportbikes. After being rescued from extinction by British financial magnate, John Bloor, the company revived itself by first offering rather conservative bikes that provided decent performance for a moderate price tag, while retaining the incomparable character that Triumphs have been known for. Those bikes sold well enough to enable the company to get back on solid financial footing, allowing its designers and engineers the freedom to create more audacious motorcycles like the Speed Triple and Rocket III.
When Triumph announced that it was taking on the might of Japan by designing a four-cylinder 600 sportbike, the world was anxious to see if the upstart British manufacturer could measure up on the competition's own playing field--an arena in which the Japanese had been fiercely battling for almost two decades. Unfortunately, that first effort, the TT600, fell well short of the mark, graphically displaying the difficulty of overcoming that development head start. Even extensive updates to the engine and chassis with the second- and third-generation Daytona 600 and 650 failed to significantly close the gap as the Japanese continued their rapid and manic
development/refinement of the four-cylinder 600 sportbike.It didn't take long for Triumph to decide that
conventional methods wouldn't work in this case. So the company went back to the drawing board and the philosophy
that has brought it the greatest success: being different than everyone else, the heart of which consists of the
company's now-trademark three-cylinder engine configuration. The latest result of this philosophy is the new
The Daytona 675's swingarm...
The Daytona 675's swingarm is fabricated from two die-cast halves and is longer than the old Daytona 650's swingarm, despite the 675's short 54.8-inch wheelbase. Swingarm pivot is adjustable via inserts, but you'll have to make your own. Triumph doesn't offer any accessory pieces.
Daytona 675--and it's not only different, it's damn good. Good enough that it just might set a new standard for
"MUST BE A THREE-CYLINDER ENGINE"
The single-injector Keihin...
The single-injector Keihin throttle bodies don't use a secondary throttle valve to control intake fluctuations, presumably because a triple's intake pulses are a little easier to deal with, and the additional flywheel effect dulls much of any abruptness in the throttle response. Regardless, the 675's fuel injection was pretty smooth in all situations.
The Triumph's valves are set...
The Triumph's valves are set at a narrow included angle of 23 degrees, with single valve springs controlling them for less frictional losses. Slipper-skirt pistons force a fairly high 12.65:1 compression ratio. Note the difference in shape between the intake and exhaust valves.
The Triumph's underseat exhaust...
The Triumph's underseat exhaust shares an opening in the swingarm with the rear shock. Although there's heat shielding, we found the back and inner portion of our thighs getting a little cooked on the street ride.
Radial-mount, four-piston Nissin calipers biting on 308mm stainless steel discs provide outstanding braking power. Overall feel, progressiveness and modulation were superb, even during extended racetrack thrashings.
The Daytona 675's instrument...
The Daytona 675's instrument panel features a row of seven blue shift lights to the upper right of the analog tachometer that illuminate simultaneously (they are adjustable for rpm activation point). LCD display functions also include a 99-lap timer.
The stock underseat muffler...
The stock underseat muffler sports both an exhaust valve and catalyzer in its construction, yet emits a nice but unobtrusive bark. Despite outward appearances, there is no room underneath the passenger seat.
By throwing out the conventional playbook and deciding that the new middleweight Daytona would be a triple,
Triumph gained some major benefits. Having only three instead of four cylinders meant the new engine would be
narrower, which could help make the bike's midsection slimmer, as well as improve aerodynamics due to its smaller
front profile. Possessing one less cylinder also means that the engine can be made much lighter, and the narrower
crankshaft can provide less gyroscopic effect for better handling agility.
There is one big disadvantage, however. It's far more difficult to achieve the same horsepower numbers using the
same engine displacement with fewer cylinders. The design brief not only specified a three-cylinder engine, it
also had to have strong midrange torque to go along with serious peak power; this required Triumph engineers to
increase the new Daytona's engine size. So the new Daytona not only gains notoriety for being the first
three-cylinder middleweight sportbike but also for its distinctive engine size of 675cc.
The new Daytona 675 is also the first Triumph to make extensive use of CAD/CAM (computer-aided design/manufacture)
and FEA (finite element analysis) technology in its design and development. This means that far fewer prototype
parts have to be made because much of their fitment and performance can be simulated in a computer program before
actually being fabricated, drastically shortening development time. In the Daytona's case, Triumph claims the
completely all-new engine went from early design sketches to full running prototype in less than six months!S
porting a bore/stroke of 74.0 x 52.3mm, the 675cc triple's cylinder head features a shallow included valve angle
of 23 degrees, with 30.5mm intake valves and 25.5mm exhaust valves controlled by single valve springs on both
sides. The exhaust valves have 4mm stems and are made from a nickel-based material that allows them to withstand
higher temperatures. The intake ports are CNC-machined for precise shape and flow. Forged pistons utilize rings
coated with DLC (Diamond-Like Coating, the same material used on fork tubes) to reduce friction that can cause
"flutter" at high rpm, and force a compression ratio of 12.65:1. Nutless connecting rods are used for less
reciprocating weight and higher strength.
The closed-loop fuel injection system (a lambda sensor located just inside the entrance to the collector measures
oxygen output and alters the fuel curves accordingly) is a Keihin unit with single-butterfly-valve throttle bodies
measuring 44mm using single 12-hole injectors. The fuel injection inhales through a ram-air induction system with
a centrally-located intake duct in the nose of the fairing directing air straight through the frame's steering
head into the airbox. An electronically controlled flapper valve in the forward portion of the duct helps control
intake noise and maximize intake velocity at lower rpms. Spent gases are fed into a three-into-one stainless steel
exhaust system equipped with a valve in the underseat can to help low-end torque, and a single catalyzer to assist
in meeting stringent Euro-3 emissions standards.
Following current engineering trends, the new Daytona engine utilizes a stacked gearshaft arrangement to
significantly shorten its length and overall size. Also saving weight and additional packaging is a combination
water/oil pump, although some of those savings were surely eaten up by the crank-driven counterbalancer shaft that
is used to help cut vibration. All told, the 675 triple is claimed to pump out 123 horsepower at 12,500 rpm, with
53 ft.-lbs. of torque at 11,750 rpm.
The all-new aluminum perimeter chassis is fabricated using closed- and open-back castings for the desired amount
of strength and flex that promotes improved cornering feel. It is claimed to be 21 percent narrower and an
astounding 19.4 pounds lighter than the old 650 Daytona frame. The two-piece cast swingarm has an adjustable pivot
(although Triumph doesn't offer accessory units; any changes require plates fabricated by the customer) and
measures 574mm in length. Rake and trail numbers are fairly aggressive at 23.5 degrees and 87mm, respectively,
especially when paired with the short 54.8-inch wheelbase. A non-adjustable steering damper located under the
steering head ensures some stability.The fully adjustable 41mm Kayaba inverted cartridge fork holds a
3.50-inch-wide cast aluminum front wheel sporting 308mm brake discs clamped by radially mounted (and radial master
cylinder-actuated) Nissin calipers with differential-diameter pistons sporting a friction coating for improved
action. The swingarm is controlled by a fully adjustable single Kayaba piggyback-reservoir shock with a
5.50-inch-wide rim and 220mm rear brake disc. Both wheels are shod with an OE-spec Pirelli Supercorsa Pro tire, a
120/70ZR-17 front and 180/55ZR-17 rear. Claimed dry weight of the Daytona 675 is 364 pounds.