carburator tuning

GoldenMotor.com

hcrft

New Member
Jan 4, 2013
28
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NORTH CAROLINA
im looking for advice and help on fuel setting for my bike. i have a CNS carb installed and running, and want to know how to get optimum performance out of it.
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
CNS carbs are hard to tune. They were designed to meet epa requirments, more than actually make your motor run well. The eaisest way to get optimum performance is to toss it in the can, and replace it with an NT of a Speed carb. Be sure and buy a new throttle cable for a NT at the same time. The throttle cable for a CNS is different. The cable for a NT, or Speed carb is the same.
 

wan37

Member
May 29, 2011
354
4
18
Illinois
Interesting biknut,cables are different.I would like to know the difference?Please tell me that could really help me!
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
Interesting biknut,cables are different.I would like to know the difference?Please tell me that could really help me!
The CNS cables have longer distance from the housing end, to the end of the cable.

If you're capable of cutting the cable and soldering on a new end you could use the old cable. You would need to cut off about 1/2"- 1" of cable.
 

wan37

Member
May 29, 2011
354
4
18
Illinois
I also have got a throttle cable with a bigger end that goes in the throttle housing.why is that?
 
Last edited:

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
Yes, toss the CNS and get an NT (less than $20 delivered on eBay). However, I can say that the v3 CNS throttle cable DOES indeed fit the NT Speed carb; I switched mine out no probs.
 

survive1990

New Member
May 14, 2013
29
0
0
tucson
CNS carbs are hard to tune. They were designed to meet epa requirments, more than actually make your motor run well. The eaisest way to get optimum performance is to toss it in the can, and replace it with an NT of a Speed carb. Be sure and buy a new throttle cable for a NT at the same time. The throttle cable for a CNS is different. The cable for a NT, or Speed carb is the same.
whats the difference between the speed and the nt ?? i have a cns and i hate it!! i cant adjust the needle its runing rich which should i get.. im thinking the nt??:-||
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
whats the difference between the speed and the nt ?? i have a cns and i hate it!! i cant adjust the needle its runing rich which should i get.. im thinking the nt??:-||
Your bike will run great with either an NT or a Speed carb. Both carbs use the same jets and throttle cable.

A speed carb is about 2mm bigger than a NT. I suspect an NT gives a little better gas milage. A speed carb seems to have a better idle. That's mainly why I like it. Power wise there's not much difference between the two, at least with pretty stock motors.

A speed carb has a built in petcock which some people have had trouble with. I never use the one on my carb, and just keep an eye on the banjo bolt to make sure it's always tight.

I also like to use a shorty intake manifold with these carbs, because of the oring, but it's not really necessary.
 

survive1990

New Member
May 14, 2013
29
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0
tucson
thank you guys i just ordered a nt carb i have a angled manifold im not shure if the carb and the shorty would fit inside the frame it would be really close...