A look at the specs shows that the Street triple is a stripped down sport bike and the Ninja is a mid size standard
Kawasaki
Four-stroke, liquid-cooled, DOHC, four-valve per cylinder, parallel twin
Displacement 649 cc
Bore & Stroke 83.0 x 60.0 mm
Compression Ratio 11.3:1
Cooling Liquid
Fuel Injection Digital fuel injection with two 38mm Keihin throttle bodies
Ignition Digital CDI
Transmission 6-Speed
Final Drive O-Ring Chain
Frame Semi-double cradle, high-tensile steel
Rake/Trail 25°/4.2 in.
Wheelbase 55.5 in.
Front Suspension / wheel travel 41mm hydraulic telescopic fork / 4.7 in.
Rear Suspension / wheel travel Single offset laydown shock with adjustable spring preload / 4.9 in.
Front Brake Type Dual 300mm Petal Disc with 2-Piston Caliper
Rear Brake Type Single 220mm petal disc with single piston caliper
Fuel Tank Capacity 4.1 gal.
Seat Height 31.1
Curb Weight 449.8 lbs.
Overall length 82.7 in.
Overall width 29.9 in.
Overall height 47.2 in.
Color Candy Lime Green, Ebony, Metallic Island Blue
Warranty 12 months
Triumph
TypeLiquid-cooled, 12 valve, DOHC, in-line 3-cylinder
Capacity675cc
Bore/Stroke74 x 52.3 mm
Compression Ratio12.65:1
Fuel SystemMultipoint sequential electronic fuel injection with SAITransmission
Final DriveO ring chain
ClutchWet, multi-plate
Gearbox6-speed, close ratio
Frame Aluminum beam twin-spar
Swingarm Braced, twin-sided, aluminum alloy
Front Wheel Cast aluminum alloy 5-spoke 17 x 3.5in
Rear Wheel Cast aluminium alloy 5-spoke, 17 x 5.5in
Front Suspension Kayaba 41mm upside down forks, 120mm travel
Rear Suspension Kayaba monoshock with adjustable preload, 126mm rear wheel travel
Front Brakes Twin 308mm floating discs, Nissin 2-piston sliding calipers
Rear Brakes Single 220mm disc, Nissin single piston caliper