NC35 HRC emulsion tubes

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jake
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Re: NC35 HRC emulsion tubes

Post by jake » Tue Dec 30, 2008 12:04 am

Jon wrote:From Dellorto's manual, who have a pretty good handle on tuning slide type carburettors;

"The atomisers fitted to Carburettors intended for four-stroke engines are manufactured with different types of side drillings because the positions of these holes affect acceleration response.
Atomiser holes positioned high up cause a weakening in the mixture since they are above the float chamber fuel level and only let air in; conversely,holes lower down cause mixture enrichment because they are below the chamber fuel level and draw fuel from the well to the barrel.
The result is that, to weaken the mixture under acceleration, atomisers with holes drilled higher up are required, while to enrich the
mixture, atomisers with holes lower down are needed. The holes' diameter determines how long the well takes to empty and it is
therefore also necessary to select a suitable size."

Atomisers = Emulsion tube

If it is running rich in the 6 to 10k range I would have thought you were still looking for a needle that is thicker in the tip or dropping it down a notch.


regards
jon
excellent Jon, thankyou very much.
Without having some needles machined...im probs stuck with the ones i have.
The problem with them... they are longer than standard needles( great we thought, will lean it up a treat)... but we are on the middle clip, go any lower and it gets richer...
Id like to get them to work somehow because we are getting great peak power out of them. I think i will experiment with some spare emulsion tubes.thanks again

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Jon
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Re: NC35 HRC emulsion tubes

Post by Jon » Tue Dec 30, 2008 12:45 am

[quote="jake
... but we are on the middle clip, go any lower and it gets richer...
[/quote]

Sorry I meant drop the needle / move the clip up one notch.

regards
jon
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jake
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Re: NC35 HRC emulsion tubes

Post by jake » Tue Dec 30, 2008 11:49 am

yep, that what i meant too!
if i put the needle on the richest setting, i can lean it off upo to the needles mid point. move the clip up again and it gets richer again. Its weird. So the most effective clip posistion is the middle setting.So im hoping if i block one of the lower holes in the emulsion tubes it may push it in the right direction.
also, would lowering the float bowl height have a similar effect?
jake

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Jon
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Re: NC35 HRC emulsion tubes

Post by Jon » Tue Dec 30, 2008 9:30 pm

Seems very odd to drop a needle and then get a richer result.

How is your intake setup?

What carbies are you running?

How are determining rich/lean O2 sensor?

How are you loading the bike?

IMHO inertia dynos and O2 sensors are not a great combination for fine tuning fuel as the time spent in each rev range is very small and the time delay for the exhaust gas to get back to the sensor then the sensor to register change can mess with your head. Great for getting close but not for fine Tuning.
Inertia dynos are brilliant for back to back power runs to see if the change you have made is better or worse.
O2 sensors and loggers are great on a brake dyno where you can load it at each rev range and let it stabilise or vehicle mounted to log a heap of data from a few laps around a track to be sorted by rev range and throttle position/Map sensor to form a matrix to analyse.

The latest software (which I haven't used yet) for my O2 logger is @ http://www.devtechnics.com/winlog.htm

regards
jon
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Cammo
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Re: NC35 HRC emulsion tubes

Post by Cammo » Wed Dec 31, 2008 1:02 am

Good info in this thread Jon.

Does anyone have info on the nc35 hrc emulsion tubes. Less or more holes than standard?
"It's just a ride" Bill Hicks

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RickOliver
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Re: NC35 HRC emulsion tubes

Post by RickOliver » Wed Dec 31, 2008 11:51 pm

NC35 HRC emulsion tubes have two through drillings (i.e. four holes in two pairs 180deg apart) one at 15mm and the other at 12.5mm from the top of the tube (i.e. the opposite end to the main jet).

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