ORIGINAL: ec121
I usually make an extended carb arm to increase the leverage of the servo, and also to match the servo arm length to the carb arm length. I don't like trying to adjust the little short Walbro throttle arms with a longer servo arm. The holes in the carb arm will usually tap out to 4-40 or 3mm threads. Then cut out a piece of aluminum the shape I want and mount it to the carb.
You really don't need to increase the leverage on a throttle servo. But it will keep your end points from being ridiculously low therby decreasing servo resolution