Gt 750 Bs40 needle position?

[T350guy]

After taking apart the carbs to fix a plugged circuit I noticed the needles were sitting differently than the LH side.
I found the needle clip on the LH to be in the 3rd notch the middle and RH in the 4th notch.
These are 75 later carbs..110 mains L&R and 107.5 middle..45 pilots ..BUT the throttle valve is 110..The 74 is 120.
What was the reason from going from the 3rd notch (74) to 4th notch 75 on? Throttle valve?
Trying to figure 3rd or 4th
Thanks

[Suzukidave]

Here is lots of info on the BS carbs http://www.oldjapanesebikes.com/mraxl_G ... cover.html" onclick="window.open(this.href);return false;

[tz375]

Good question that I suspect none of us know for sure unless we worked in testing department in Suzuki back in the day.

We can deduce that the change in throttle valve changed the point at which the bypass holes interact with the slow and intermediate circuits. A change in throttle valve probably required the change in slow jets because it applied a stronger signal to the pilot jet. That in turn required the mixture screws to be further out allowing more mixture to flow. So it's easy to rationalize how those changes worked together. I would guess that it was the first attempt to cure the slow speed bucking/surging.

Raising the needle from -3 to -4 may have been an attempt too richen up part throttle conditions for some other reason such as driveability or it may be that the different throttle plate has an effect all the way up though the midrange too that needed to be compensated for.

[T350guy]

I have decided to go with the 3rd notch and try it..