A carburetor with rotary valve includes an idle adjustment needle with an eccentric hole, accordingly a special adjustment tool used for idle adjustment needle has an eccentric boss; a carburetor with rotary valve includes an idle adjustment needle with an eccentric boss, accordingly a special adjustment tool used for idle adjustment needle has an eccentric hole. The idle adjustment needle must be cooperated with the special adjustment tool to carry out the adjustment, thus non-professional user can not casually adjust the fuel oil needle without the special tool, so that the engine can be maintained in the best setting condition to ensure the engine exhaust to meet the environmental protection requirement.

A fuel regulator includes a limit cap which is attached to a needle valve which is inserted into a regulation hole. In an inner peripheral surface of a second hole portion of the regulation hole, a restriction groove and a guide groove which extends from the restriction groove through an outer surface of a main body portion in an axial direction of the second hole portion are formed. A projecting portion which is inserted into the restriction groove is formed on an outer peripheral surface of the limit cap, and the projecting portion is capable of passing through the guide groove, and in the main body portion, a cast hole which extends from the restriction groove through the outer surface of the main body portion in a direction intersecting the axial direction of the second hole portion is formed.

A fuel regulator includes a limit cap which is attached to a needle valve which is inserted into a regulation hole. In an inner peripheral surface of a second hole portion of the regulation hole, a restriction groove and a guide groove which extends from the restriction groove through an outer surface of a main body portion in an axial direction of the second hole portion are formed. A projecting portion which is inserted into the restriction groove is formed on an outer peripheral surface of the limit cap, and the projecting portion is capable of passing through the guide groove, and in the main body portion, a cast hole which extends from the restriction groove through the outer surface of the main body portion in a direction intersecting the axial direction of the second hole portion is formed.

A flow control restrictor includes: a needle valve; and a limit cap which is made of metal and attached to the needle valve. In the needle valve, a first shaft portion which is made of metal and screwed into a regulation hole and a second shaft portion which is made of metal and housed inside the regulation hole are formed. On the second shaft portion, a first projection-and-recess portion is formed, and a pressed portion made of resin is provided on the first shaft portion side relative to the first projection-and-recess portion. The limit cap is fitted onto the second shaft portion. On the limit cap, a projecting portion which is inserted into a restriction groove of the regulation hole and a second projection-and-recess portion which is engaged with the first projection-and-recess portion are formed. The pressed portion is pressed against an inner peripheral surface of the limit cap.

A flow control restrictor includes: a needle valve; and a limit cap which is made of metal and attached to the needle valve. In the needle valve, a first shaft portion which is made of metal and screwed into a regulation hole and a second shaft portion which is made of metal and housed inside the regulation hole are formed. On the second shaft portion, a first projection-and-recess portion is formed, and a pressed portion made of resin is provided on the first shaft portion side relative to the first projection-and-recess portion. The limit cap is fitted onto the second shaft portion. On the limit cap, a projecting portion which is inserted into a restriction groove of the regulation hole and a second projection-and-recess portion which is engaged with the first projection-and-recess portion are formed. The pressed portion is pressed against an inner peripheral surface of the limit cap.