with the big blue arrow, they key word is MAIN source of vaccum, as well as CLOSER to atmospheric pressure. Any air pressure below atmospheric is going to draw some fuel out. So fuel is still coming out of the port of the low needle, even if its at a reduced amount because of the reduction of vacuum due to the throttle plate being open.

If the low speed needle gives absolutely NO fuel at the top end, then the company that wrote the DLE20 manual are wrong, the guys at Indiana Tiny Gas Engines are wrong and the knowledgeable people at Valley View RC are wrong.

My comment about the aircraft and forced induction have nothing to do with this. It was simply my response to ahicks about the term "vacuum pressure". I understand very well how and why forced induction works and why its used on aircraft. At idle there is not boost (pressure) in the manifold on a turbocharged engine because as you said, the turbo is not turning fast enough to move much air. And at low throttle is isnt getting boost because the throttle plate is blocking air from going in (if you watch a boost gauge on a diesel engine, which does not have any type of throttle plate, it will see a little boost even when cruising at low throttle). Which is the reason why my (centrifugal) supercharged engine doesn't see boost at low throttle. The supercharger rpm is directly related to the engine rpm and is moving more air than the engine (the engine is a pump too), even at idle. Since the throttle plate or "butterfly" is blocking the air put out by the supercharger, a bypass or blow off valve is employed to relieve the excess pressure. And also to keep the supercharger from being over pressured when the throttle is snapped closed from WOT, which would cause a surge and would cause impeller to housing contact and cause all kinds of damage to the supercharger....

But as before, that has nothing to do with the discussion. Im going to keep adjusting my high end needle last to make sure its right, and you two can do what ever you want. Obviously unclecrash isnt going to be swayed from the way he has decided to do it 35 years ago. So Im not gonna argue any more.

If someone like JediJody comes in and says that the low needle has no effect on the top end, then Ill research some more and may reconsider. I think this subject has been discussed on this very thread a couple hundred pages back or so. Maybe I'll scan through it if Ive got time.