Serval and Cub Kit Published 09/22/2021 at 2197 × 2560 in 4 -10mm Cub Cylinder Kits Firstly Cub cylinder packages are recommended for use with race gas. Secondly Redline has tested 4mm motors at well over 100HP on race gas with a wide spread of power. Lastly on alky the 4mm Cub package will make 115HP with good supporting parts.