The Buell Thunderstorm is a modern air/oil/fan-cooled V-Twin powertrain utilised in the Buell XB motorcycle platform that includes the Firebolt, Lightning and Ulysses model families. Two versions of the engine are offered. The Thunderstorm 1203 displaces 1203cc and produces 103 hp at 6800 rpm and 84 ft. lbs. of torque at 6000 rpm.
The Thunderstorm 984 displaces 984cc and produces 92 hp at 7500 rpm and 70 ft. lbs. of torque at 6000 rpm. Both are tuned to deliver a broad, flat torque curve that makes abundant power available to the rider at almost any speed, reducing the need for down shifting and providing strong acceleration in any situation. Both engines feature electronic fuel injection and dry-sump oiling. The Thunderstorm 1203 is equipped with the Buell InterActive Exhaust system, which utilises a valve in the dual chamber muffler that is controlled by the ECM and adjusts exhaust flow according to riding conditions to smooth torque delivery and optimise engine power. For 2008 the Thunderstorm 1203 redline is increased to 7100 rpm from 6800 rpm, giving this engine an even broader powerband, and riders the ability to accelerate longer and down shift at a higher rpm. The rpm redline of the Thunderstorm 984 remains 7500 rpm. For 2008, the following changes have been made to both the Thunderstorm 1203 and the Thunderstorm 984: New Timing System. The timer cover is eliminated, as the engine is now crank timed from a new crank position sensor, which eliminates the need for manual timing, reducing main-tenance costs. The ECM actively monitors and adjusts timing based on driving environment. The new sensor makes 30 reads per revolution, compared to the previous two reads per revolution, for more precise control of fuel mapping and timing to conditions. More Robust Crankpins. The size of the crankpins is increased to 1.50 inches from 1.25 inches. Oiling System Upgraded. A higher output oil pump supports oiling to the new crankpin area. The new pump is driven off the crank, a design based on the Buell XBRR production racing motorcycle. A new eight row oil cooler offers enhanced cooling performance. New DDFI 3 ECM (Engine Control Module).
A new ECM with increased computing capacity. DDFI 3 actively controls and monitors the TPS (throttle position sensor), IAC (idle air control), and timing. DDFI 3 automatically zeros the TPS and adjusts fuel metering for smoother idle, eliminating service intervals and reducing the cost of ownership. A new progressive throttle cam and new throttle cables provide smoother throttle input from stops, and less rotation to full throttle.