40cc 4-stroke gasoline engine for the X-PRO Mini Bike More efficient & longer lasting Greener, less polluting Our 40cc 4-stroke engine for the X-PRO 40cc mini bike is a great replacement for a damaged or missing gas engine In addition to the X-PRO, this powerhouse is especially good if you are building a custom project Our 40cc 4-stroke engine for the X-PRO 40cc mini bike is a great replacement for a damaged or missing gas engine. In addition to the X-PRO, this powerhouse is especially good if you are building a custom project. These 4-stroke engines are often the better choice than their 2-stroke cousins because they are more efficient and last longer. In addition, 4-stroke gas engines like our 40cc model are “greener”, and less polluting. As such, they are usually legal in localities where the older 2-stroke engines are not. If you also need a transmission for this 4-stroke engine our Gearbox Transmission for 40cc 47cc Engine Mini ATVs, Dirt Bikes, Pocke