Hsr42 Float needle for draw through 2.3 vs 4.2 vs 4.5

[BoostedBikes]

After looking through countless forums for jetting advise for a 1040cc draw through turbo setup im doing. I found a few mentions of the 2.3 float needle being a must. I ordered all sudco had to offer for float needles left to right (2.3,4.2,4.5) and the 2.3 was by far the smallest of the bunch which leaves me scratching my head a bit. Is there some kind of regulating effect the 2.3 gives with a fuel pump that makes it viable? Seems like the most counterintuitive solution and i'd really want to install the 4.5 float seat which has the biggest hole. Keep in mind that the needles themselves are the same between the bunch I checked that already

[mikeyd]

I had to use the smallest one so it wouldn't overflow the carb. A must when using a fuel pump, even at something as low as 5 lbs of fuel pressure.

[Gixer1460]

For a bike carb - even a HSR - 5psi FP isn't low!

1.5 - 2.5psi max is usual pumped pressure!

[FJD]

+2 on this subject, the bigger hole will be difficult to keep tight 

[mikeyd]

12 hours ago, Gixer1460 said:

For a bike carb - even a HSR - 5psi FP isn't low!

1.5 - 2.5psi max is usual pumped pressure!

True 1460. When we were using a s+s super b carb, 2-3 psi. When switching to hsr42, was able to realize 6-7 psi. Just messing around on the dyno with it, that's where the bike liked it best and worked very well at higher rpm's.

[Gixer1460]

Hear what you're saying - Phil 'Woody' Wood used to run similar pressures on the Big CC Turbo / Nitrous Bandit but couldn't run the FP all the time as it would flood the engine at low / mid rpm's - proper juggling act, starting and staging!