Heli-coil should NOT be a problem if your are careful (use a drill press to get the hole plumb, and NOT too deep). I have heli-coiled several of these carbs.

If you tap for a #12, you will have to drill out the hole(s) in the airhorn as well, just adding to the possibility of error.

And if you put in non-standard screw size, the next rebuilder will NOT salute you with your favorite beverage! wink

Heli-coils come in 3 different lengths (short, standard, long). Use the short ones in the YF.

Here is site that specifies drill sizes for heli-coils:

https://www.carbidedepot.com/formulas-tap-helicoil.htm

Jon.


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