I did the bk mod yesterday, it was extremely easy. I used a 5mm allen screw and spring from my local auto parts. The two issues I came across that I didn't see listed anywhere was the accelerator pump needs to be primed if it runs dry and you also have to cut a notch in the plastic cover over the linkage. I think it was under $10 for the tap, drill bit, screw and spring. The whole job took about 5 minutes after the carb was off.