Service: carburetor - cutting over-size M8 x 0.75 screw thread for idle mix screw ►see details

Standard size of idle mix screw thread is M7 x 0.75

When the M7 screw thread is damaged, it can be enlarged to M8 x 0.75.

Drill size is 8 - 0.75 = 7.25 mm. 

Drilling and cutting the M8 screw thread should be left to a specialist: the new screw thread must be perfectly aligned with the bore in the carburetor housing.

Only half of this over-size idle mix screw has M8 x 0.75, so the original M7 jam nut, sleeve and cap are maintained.

 Idle mix screw thread repair - YouTube

A 7.2 mm drill and M8 x 0.75 mm tap can be found here: M8drill-tap