I definitely wouldn't drill 2mm holes in the butterfly. The exact same effect can be gained by using the air by-pass screws. I find I can't open my air-bypass screws much before the idle gets to high even with the idle screws wound out and springs on the linkage.
Make sure everything is ultra clean. The whole "my webers fall out of tune" thing is actually "I have crap fuel filters so crud blocks my idle jets". Weber idle jets block real easy.
I have never heard the fuse wire trick either.
I would put in the 60's and then try opening the air-bypass screws to lean the mixture back out a little.
Wes -
www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control...
🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.