Super Twin Top Fuel Drag Bike
FIM-Super Twin Top Fuel Drag Bike is the official classification in Europe for Drag Racing using Nitro methane fuelled 2 cylinder Motorcycles.
No limitations are put on the single two cylinder engine regarding configuration, exept these rules:
RR09 UEM Technical Rules for Drag Bikes 2008 14-01-2008
In the early years (85-90) most riders were using Harley-Davidson engines with reinforced blocks and bored out to accommodate as large cylinders as possible. The crank assembly was "stroked" to maximize the length of the stroke and thereby creating an engine with an incredibly big volume (98-122 ci).
The fuel was everything from the predominantly used ordinary gasoline to Nitro methane, occasionally even combined with Nitrous Oxide (also known as Laughing Gas). Not many on the circuit had a very good idea how things worked. Not strange considering everybody's level of inexperience. An Elapsed Time (ET) for the ¼ Mile under 9 seconds was something very exotic.
As the interest for the sport grew and gained in popularity more people got involved and the ET's started dropping. Engines increased in volume (122-158 ci). New fuel injection and ignition systems were added. The stress on the engines were approaching a critical point as they reached overload. Break downs became frequent.
More and more the teams drifted toward pure professional project with components that were mostly imported from the United States. Some teams chose to build their own power plants according to their own ideas.
The last few years the ET's have dropped dramatically, and now many of the riders driving consitant 6,5 to 6,8 seconds over the ¼ Mile.