Why not a needle change?

[Guest]

Okay, I may have skipped a step by not doing a thorough search(did a quick search yesterday though), but amidst all the tuning tips about rejetting and shimming needles, something dawned on me:

Why not re-needle? Why not swap air bleed screws?

I know cars are markedly different from bikes, but quite honestly the needle is essentially the equivalent of Edelbrock's metering rod - you can change them out to match your fuel curve needs. Likewise, the air bleeds are found on Holleys, which are more tuneable still.

So am I just blowing more hot air? Or is there something to this train of thought?

[Joe H]

Because its easier to let someone who's entire life is dedicated to finding and manufacturing needle that will work with a know combination

Many guys with VM or RS carbs switch needles there are excel sheets made by some to compare needles and needle jet combos.
It gets pretty tricky trying different needles and needle jets…don't ask how I know..LOL
jetneedlearea-4.xls

[GregT]

Okay, I may have skipped a step by not doing a thorough search(did a quick search yesterday though), but amidst all the tuning tips about rejetting and shimming needles, something dawned on me:

Why not re-needle? Why not swap air bleed screws?

I know cars are markedly different from bikes, but quite honestly the needle is essentially the equivalent of Edelbrock's metering rod - you can change them out to match your fuel curve needs. Likewise, the air bleeds are found on Holleys, which are more tuneable still.

So am I just blowing more hot air? Or is there something to this train of thought?

The main reason it's not spoken of is because OE carbs generally don't have alternative needles available. Occasionally you may find a different needle used in another market - but it's not common. Dynojet have kits for some but by no means all. The main benefit IMO of using aftermarket carbs is that there is usually a selection of alternative needles available...