CNS Carb is a gas guzzler

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FractaL64

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May 8, 2013
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As much as I love the performance I get out of my CNS carb, I mean Im talking some serious acceleration, and smoother throttle response, the thing drinks gas at a disgusting rate.

How can I throttle how much fuel I'm using? I've tweaked my choke and idle, and I've tried to choke my petcock by leaving the valve barely open, but it still chugs.

Any ideas of how I can get the thing to stop drinking all my damned gas?

The old NT carb I had seriously sipped on so little gas that it took me almost a month of daily riding (2-3km) to get through a tank.
 
Greg58

Greg58

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May 1, 2011
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I agree with Pablo, do a plug check. I run a nt on one bike and a cns on the other with very little difference in fuel mileage, if the plug is black or wet your float level could be too high causing a rich condition.
 
Moto

Moto

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Jan 7, 2012
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Same issue with my 21mm phbg - she chugs gas Im serious im running a tad lean and still am probably getting something stupid like 40-50 mpg ... performance is worth it though.
 
K

KenX

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Apr 20, 2013
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Whatever kind of carb I have runs very well except gas mileage won't exceed 50 mpg I,m guessing. I would rather have a performing bike rather than worry about gas mileage.
 
xseler

xseler

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Apr 14, 2013
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Have you drilled and removed the brass plug on the left side of your CNS carb? The adjustment screw under that plug will make a lot of difference! Counterclockwise is the direction that mine needed to really wake up the Skyhawk!! Good luck!


With that being said, don't guess that ever paid much attention to the fuel mileage......I just check to see if there's enough in the tank to go where I intend.
 

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mrfubs

mrfubs

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Jun 13, 2013
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My CNS carb doesn't drink gas although I do go through a lot of it fairly quickly I'm getting peak performance and now that it runs some what like a dirtbike its going to drink gas like a dirt bike sounds about right to me. You won't gain performance with out using more fuel
 
JaxInsany

JaxInsany

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May 6, 2013
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Portland, OR
xseler said:
Have you drilled and removed the brass plug on the left side of your CNS carb? The adjustment screw under that plug will make a lot of difference! Counterclockwise is the direction that mine needed to really wake up the Skyhawk!! Good luck!


With that being said, don't guess that ever paid much attention to the fuel mileage......I just check to see if there's enough in the tank to go where I intend.
Click to expand...
I'm about to do some adjustments on that screw myself so I wanted to know what qualified as "waking up" your engine? Did you get an increase in power? More fuel efficiency?
 
xseler

xseler

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Apr 14, 2013
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Lots smoother, hardly any 4 stroking, less smoke, pulls harder, higher upper rpm's ---- still don't know about fuel mileage.....haven't checked. However, I'd assume it's using less fuel....or more fuel. Doesn't really matter to me.
 
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dodge dude94

dodge dude94

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Jun 8, 2012
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JaxInsany said:
I'm about to do some adjustments on that screw myself so I wanted to know what qualified as "waking up" your engine? Did you get an increase in power? More fuel efficiency?
Click to expand...
What is waking up an engine?


It's like pressing the "Oh-sh1t-that's-some-serious-damn-acceleration-compared-to-what-I-had-before-button."

:D

But in all seriousness, I copy what xseler said.
 
JaxInsany

JaxInsany

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May 6, 2013
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dodge dude94 said:
What is waking up an engine?


It's like pressing the "Oh-sh1t-that's-some-serious-damn-acceleration-compared-to-what-I-had-before-button."

:D

But in all seriousness, I copy what xseler said.
Click to expand...
HOLY CR*P is all i have to say after that test ride, my bike used much less gas than usual and I upped my top speed from 24 to 30 mph.... I'd say i woke up the engine pretty nicely...!!!
 
dodge dude94

dodge dude94

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Jun 8, 2012
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JaxInsany said:
HOLY CR*P is all i have to say after that test ride, my bike used much less gas than usual and I upped my top speed from 24 to 30 mph.... I'd say i woke up the engine pretty nicely...!!!
Click to expand...
haha Good to hear. Mine didn't gain any speed, but idle quality was better as well as acceleration in general.
 
xseler

xseler

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Apr 14, 2013
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JaxInsany said:
HOLY CR*P is all i have to say after that test ride, my bike used much less gas than usual and I upped my top speed from 24 to 30 mph.... I'd say i woke up the engine pretty nicely...!!!
Click to expand...

See!! I only type the truth as I know it. Now, if you want to take the next step, switch out the main jet to a #66 or a #68 --- running a #66 in mine now. Makes it even mo betta with my exhaust set-up. I believe that the stock jet is a #70.

Seems funny that the EPA mandated adjustment uses more fuel with less performance. Surely there's something comical that can be derived from this!
 
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outlawbiker

outlawbiker

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Mar 15, 2009
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i dont know if any research has been done on this,but would reed valve help?

now that we have access to bolt on reed valves i would think fuel metering would be improved because on the compression stroke its not trying to blow back into the intake and out the carb?

last time i checked they were 100 bucks,could be an expensive solution if it helped.
 
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