Here is a review of our two stroke 49 cc bike motor kit after writing it for three weeks. These 2-stroke gas motorized bike kits always need adjusting and maintenance, and you will find things breaking and needing to be repaired. In our case, the chain tensioner always needs to be adjusted, and it has fallen apart. The throttle cable broke, the choke stays on while you are riding and less you got tape it down, the exhaust manifold gasket blew out, and sometimes the gas leaks out of the carburetor into the muffler. Overall, we had to do a lot of work to keep this two stroke gas motorized bike kit on our bike working properly, but it has been a lot of fun and educational as well.