four stroke. Was a great bike starts in one good kick. when riding it will randomly lock up then you have to put it in gear to free it up just don’t wanna hassle with it right now and money is tight. I have a new carburetor that I got off of eBay that I put on it right now and the original one too. The suspension will probably need to be replaced too. It’s pretty bouncy. I have New an old plastics for it and clutch lever. I don’t know the exact mileage me and the previous owner would ride it around our neighborhood and on trails that hasn’t been used in severe races or jumps. Text me for more questions.