At what revs and/or throttle position are you seeing/feeling that difference?
In theory, the needle and needle jet are there to moderate the main jet. Normally the pilot jet and pilot air jet/adjustment control idle and just off idle. As the throttle is cracked open, the cutaway becomes the main control system and from there up to say 3/4 it's all about the needle and needle jet. Main jet does impact all the way down but main jet has to be set of full throttle operation and the needle jet spray bar height and main air jet control the fuel slope.
What the heck is a fuel slope? Well we tend to conflate revs and throttle opening and that's understandable, but we usually get things wrong because of that. At full throttle the air:fuel ratio changes as revs rise. Two strokes typically require a richer mixture at full throttle & full revs than a 4 stroke, so the air jet or spray bar are used to change how much richer or leaner it gets aas revs rise. That's what they mean by changing the fuel slope.
That's also why people say to get idle right first and then main jet at full revs. After that the needle and needle jet are used to tweak that fuel slope at lower throttle openings.
In this case, it sounds like a wrong cutaway or wrong needle jet taper or the point at which that taper starts.
Which is why I asked where is the issue in terms of throttle opening.
In theory, the needle and needle jet are there to moderate the main jet. Normally the pilot jet and pilot air jet/adjustment control idle and just off idle. As the throttle is cracked open, the cutaway becomes the main control system and from there up to say 3/4 it's all about the needle and needle jet. Main jet does impact all the way down but main jet has to be set of full throttle operation and the needle jet spray bar height and main air jet control the fuel slope.
What the heck is a fuel slope? Well we tend to conflate revs and throttle opening and that's understandable, but we usually get things wrong because of that. At full throttle the air:fuel ratio changes as revs rise. Two strokes typically require a richer mixture at full throttle & full revs than a 4 stroke, so the air jet or spray bar are used to change how much richer or leaner it gets aas revs rise. That's what they mean by changing the fuel slope.
That's also why people say to get idle right first and then main jet at full revs. After that the needle and needle jet are used to tweak that fuel slope at lower throttle openings.
In this case, it sounds like a wrong cutaway or wrong needle jet taper or the point at which that taper starts.
Which is why I asked where is the issue in terms of throttle opening.