When Suzuki developed the GSX1300R (which was launched in 1999), it set out to build the fastest mass-production motorcycle on the market, complete with a 1,299-cc liquid-cooled in-line 4-cylinder engine capable of producing 156 hp and with a top speed of 189.6 mph. The bike later gained the name “Hayabusa” (Japanese for “Peregrine falcon”), and set the foundation for a horsepower race later joined by many other German, Japanese and Italian bike makers. As competitors gained ground in the power war and regulators passed more stringent emission regulations, Suzuki engineers studied whether to reinvent the ‘Busa for 2008 or to improve upon its already formidable foundation. A keen eye on the balance sheet and die-hard fan base quickly led the engineers to understand that rather than starting from a blank page, they’d be better off tweaking the basic engine architecture in order to gain more power and to meet new emissions regulations.
They decided to leave the cylinder bore at 81 mm but to increase the stroke 2 mm to 65 mm, boosting overall displacement to 1,340 cc. Redesigned forged three-ring aluminum-alloy pistons provide weight savings of 1.4 grams each, while the revised shape of the piston crowns, combined with the use of chrome-nitride electro-plated coating, allows an increase in the compression ratio to 12.5:1 from 11.5:1, provides a smoother surface, and increases durability. Connecting rods are chrome-molybdenum steel-alloy and undergo shot peening in order to increase their strength.
Engineers modified the Hayabusa engine’s crankcase breather system to include reed valves to prevent pressure waves generated in the airbox from reaching the crankcase itself, thus reducing mechanical losses. Moving from steel to titanium valves cut the weight of each intake valve by 14.1 grams and each exhaust valve by 11.7 grams. This allowed engineers to increase valve lift to 9 mm versus 8.8 mm on the intake side and 8.6 mm compared to 7.5 mm on the exhaust. The cam chain tensioner is now hydraulically operated, resulting in improved timing accuracy and reduced mechanical noise.
In order for Hayabusa’s engine to meet the Euro 3 and U.S. Tier II emission require-ments and live up to the motorcycle’s performance roots, Suzuki developed a digital fuel injection and advanced engine management system, controlled by a 32-bit, 1,024-kb ROM processor. Twin tapered 44-mm double-barrel throttle bodies with two butterfly valves in each barrel help improve combustion efficiency and provide linear throttle response at low- and mid-range torque. Fuel is delivered via two compact fine-spray injectors (each with 12 holes) located in each throttle body barrel—the primary aimed at a 30° angle down the intake port and the secondary aimed at the secondary throttle valve to add fuel at higher rpms—for improved fuel atomization, combustion efficiency, and fuel economy. The engine management system features an idle speed control that automatically regulates the volume of fresh air fed into the throttle body idle circuit, for improved cold start performance and greater idle stability under changing conditions. The 2008 Hayabusa is expected to produce 179 hp at the rear wheel, and thus continue to set the benchmark for high-performance bikes.