A carburetor of a remote control model has a main body axially bored with an axial hole that is installed with a throttle and a second needle in its one side and provided with a female-threaded section formed at a certain portion of its other side for engaging with a male-threaded section of an adjustment valve. The adjustment valve possesses a fuel entering passage formed axially with a dead end, and an injection nozzle formed at the end corresponding to and for a needle valve of the second needle to move to and fro therein. And, the adjustment valve is directly installed in the axial hole without being accompanied with other components, effective to lower progressive tolerance between the injection nozzle and the needle valve to provide uniform fuel injection.