Some consider the 250cc F/E's or the "big twins" as the holy grail of karts!

This, the "Big Kahuna" category of karts, derives its "Twins" nickname from the use of two cylinder 250cc Grand Prix motorcycle engines such as Honda, Yamaha and Aprillia or purpose made Rotax, SGM, Hemmingway, FP, BRC and Vee-Dot  superkart engines. All modifications are allowed to the engines allowing them to produce around 90 bhp. 

Currently, 250cc Inters lap Phillip Island GP circuit (Victoria) significantly faster than 600 + bhp V8 Supercars costing hundreds of thousands of dollars to purchase and still more to maintain!!!

All this in a package that can fit into a box trailer!

Entry level 250cc F/E karts can be no more technically complicated than 250cc IC/E or even a 125cc machine, however, they do require careful tuning, really thorough preparation and regular detailed maintenance to perform reliably at anywhere near their peak.

The list of go-fast goodies available for these machines is almost endless, such as real-time data acquisition, carbon fibre and kevlar components such as wings, fairings, seats and bodywork as well as magnesium and titanium bits and pieces. Rack & pinion steering boxes, air operated gearshifters, fully floating brake discs, multi-piston brake callipers with on board bias control and on to trick programmable engine ignition systems, purpose made expansion chambers (exhaust pipes) to suit different tracks and perhaps a big wooden box full of different gearbox ratios and drive sprockets plus a couple of spare factory modified cylinders and maybe a spare crankshaft assembly thrown in to impress your friends with!

It needs to be said that most of these exotic goodies are only really necessary at the very highest level of the sport. This type of technology comes at a premium price and it is totally up to the individual to decide if the performance edge (if any) gained is worth the investment.

Grand Prix motor cycle engines, although rather highly developed, are surprisingly reliable when fitted to a superkart and will put in many kilometers of racing before significant component replacement or worse, component failure becomes an issue. Don't be fooled by GP motor cycle engines' apparent simple design and outward appearance. Those aluminium castings disguise thousands of hours and many millions of dollars in design and development. These engines can produce over 350 bhp/litre at their best but can be quite pedantic by nature and require careful tuning to perform well. The difference between a successful days racing and a costly engine failure can be no more than a couple of jet sizes, wrong sparkplug choice or a careless ignition timing adjustment!  

250cc F/E's are definitely not a beginners kart and best suit those of you with a good degree of technical knowledge and higher degree of driving ability. 

These karts can be identified by Black racing numbers on a yellow background,