Bill and w8ye, one follow up question please.

For lack of better terminology, I'll call the brass tube coming from the high speed needle side the spray bar.

If, at wide open throttle, the low speed needle is partly obstructing the spray bar, will that cause a reduction in top end performance?

In trying to understand how these two needle carbs work, it would seem that the purpose of the low speed needle is to "reduce vacuum" in the spray bar, resulting in less fuel draw, but that's just a guess.

If that were the case, given that the low speed needle is moved further into the spray bar as the throttle barel rotates toward idle, it would seem that the most important part of the taper on the low speed needle would be the portion further from the tip. If so, could one ameliorate the reduction in top end performance caused by the low speed needle, by making the inital taper, on the tip of the low speed needle, more blunt?