Custom Supermoto: The Megasgas EC 700

Supermotos are often considered the most thrilling experience on two wheels. These dirtbikes with road tires can perform incredible feats when in the hands of skilled riders. The GasGas EC 300 is already a top contender in the industry, but can it be made even better?

Sib Mustard, a German bike builder known for his love of supermotos, believes so. With a strong following on Instagram, Sib operates a shop called Haisl in Upper Palatinate. His latest creation is a custom supermoto based on the 2021 GasGas EC 300, and it's one of the wildest builds out there. Sib has taken the bike to the extreme by doubling its engine capacity while maintaining its lightweight design.

The GasGas EC 300 comes from the factory with around 50 horsepower and weighs just over 100 kilograms. That's already an impressive power-to-weight ratio. However, Sib wanted more. He acquired a racing engine from Austrian supplier Rübig, known for its high-performance engines. The original 300cc motor was replaced with a massive 699cc, two-stroke, water-cooled, single-cylinder engine. With a 100 mm bore and 89 mm stroke, this engine produces 84 horsepower. The bike was then named the "Megasgas EC 700."

To handle the powerful engine, Sib installed a new Smartcarb SC2 electronic carburetor for fuel management. The engine breathes through a custom DBR Factory exhaust system made of individually welded titanium segments. It's important to note that this bike is not street legal.

Modifications had to be made to the frame to accommodate the larger engine. Sib adjusted the mounting points on the frame to maintain balance. The result is a custom swingarm made from aluminum and a new rear shock absorber mount. The estimated weight of the bike is 120 kilograms, still incredibly lightweight considering it has 80 horsepower.

What's even more insane is that Sib plans to continue working on the Megasgas EC 700. His next project is to add a turbocharger, which will likely result in power figures that are off the charts. It's highly possible that the Megasgas EC 700 will exceed the one horsepower per kilogram ratio.