It is based on a West Coast Choppers El Diablo series bike and is the vehicle of choice for The Angels of Death. One of the most radically designed choppers in the game, the bike features a flame-based rim design.
The Hellfury handles similarly to the Freeway. It turns very widely, even at low speeds. However, it has a fast top speed, and can easily win races.
Strangely, this bike is used by The Lost in TLAD, but in GTA IV and TBoGT it is used by the Angels of Death. It is even more strange that Johnny rides the Hellfury in GTA IV.
This bike is owned by Johnny Klebitz in GTA IV, but in GTA TLAD, he rides a customized Hexer.
It's interesting to note in TBoGT that whilst Luis can get on the bike on either side, he gets off on the right-hand side. It is well-known amongst bikers that you always get off on the side of the kickstand and never on the side of the exhaust as you can burn your leg and if you catch the bike with your leg the kickstand helps to stop it fall over. This could be explained by the fact motorcycles aren't Luis's 'native' vehicle type.
Relating to the previous point, it's also interesting to note that when you exit the bike in the engine-off state, it falls to the left side as if held up by the kickstand, but if you look closely the kickstand remains in the up position.