The Needle Thread

[superlite]

Not knitting related

So an old thread re-surfaced and reminded me of some needle work (ahem) that I was doing a while back. I've measured most of the carb needles available to suit NC30 carbs (HRC and OE). I've just re-discovered the data, so I'll slowly put it all together and post it here as I go. So in the end we should have a collection of profiles for all the different needles in one spot.

I know that personally, my needle choice comes down to seat of pants testing and what others are running. But if we know the needle profile and how that affects fuelling, we should be able make a more educated choice rather than guess with trial and error (i.e. turn these measurements into something qualitative). Calling all tech heads

So to kick off, here's a comparison of one of the standard NC30 needles (J51B) and a HRC SS needle (8ZF). There is only a very slight difference in base diameter between the two. There is an obvious difference in length. But the key difference is in the tapers - 8ZF will run noticibly richer than the stock needle.

[Cammo]

That means more to me than seeing individual measurements, very nice!

Let's see all the needle measurements on a single graph!?

I'd be very interested to see how the nc21/24 needles compare to the hrc items.

[superlite]

Let's see all the needle measurements on a single graph!?

Whoa, slow down turbo! It took two years to get the first graph up

That is the plan though.

[Neosophist]

Coming soon in 2012

[CRM]

lol i am gonna keep a beady on this. i have some needles i dont mind sharing
i will go have a rummage see what i have

[superlite]

For those that are wondering, I won't be comparing the J51A and J51B stock NC30 needles with each other. J51B is 0.1 mm longer than J51A - aside from that, they're identical. They are a good reference for other needles though.

Here's another one: Stock NC21 8ZC plotted against the NC30 HRC SS 8ZF. Identical length, slightly different profile and a significant difference in diameter where it counts. Perhaps a good (and cheap) upgrade for a road bike with mild mods though?



Some slightly more exotic needles coming soon............

[Cammo]

Nice.

Can we see J51# vs NC21 8ZC? Obviously there's a length difference, but would like to see if there's any other difference.

How many measurements are you taking of each needle diameter to get these graphs?

[Old Painless]

Why does the graph start at 6mm wide ?

[superlite]

Why does the graph start at 6mm wide ?

I'm still getting to grips with the way I stored the data 2 years ago! I think the idea early on was to graph the entire profile, i.e. both sides of the needle.

EDIT: The graphs are not meant to visually represent the needle (symmetrically), but rather the actual diameter of each of the needle sections. I could display them as visual profiles. i.e. both sides of the needle, but it wouldn't mean much as the vertical axis would be displayed in positive and negative values and require doubling to extract the real values

[CMSMJ1]

great thread. can we sticky it please mods?