Lectron makes some pretty cool externally adjustable carbs, for motorcycle apps. I have one on my CR500, and there is a definite power gain when you are able to adjust without taking out jets and needles. When you are constantly disassembling the carbs, there is a tendency to leave in a "close setting", because tearing down the carb, one more time is just too much effort. The only downside to the Lectron is price.
