Metering rods are available.

The first step is to determine the ID number of your specific carburetor. On the YF, this will normally be stamped (not raised) on the center section (bowl) of the carburetor. The ID number will be in the format of either 3 or 4 digits, followed by the letter S as in (S)am. Example 967s or 2101s.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop