Each year the Small Engine Builder's Dyno Challenge brings kart and mini bike engine builders together so they can test talent and ability. RetroMod Garage sponsors the 275cc Open Modified rules, which cap displacement at 275cc instead of 310cc so more people can enter with less custom fabrication and fewer custom parts. Crankcases must be cast blocks only with no billet, though a billet side cover is allowed. Heads may be billet or cast with no restrictions on modifications. Fuel is carburetor only, pure methanol with no additives, and fuel will be provided. Ignition is factory-style analog or PVL digital, with no CDI or programmable timing controllers. Exhaust has no restrictions.
