Upgraded Carb

Clotho

Member
Joined
May 12, 2008
Messages
51
When I purchased my Powerking kit I paid the extra for the upgraded carb. It is a bit larger and has a cable operated choke. This carb has an idle adjustment as well as another adjustment beside it. Does anyone have any documentation on this carb? I would like to tune it a bit but I don't know anything about it. The lean/rich setting on the pin is pretty much the same as the old style. I just would like to know what this other adjustment is for.
 
B

BSA

Guest
I was always under the impression that the upgrade carb had a mixture screw aswell as idle screw.

BSA
 

Clotho

Member
Joined
May 12, 2008
Messages
51
Here are two photos of the carb. I pushed the fuel filter out of the way for better viewing. The screw on the right is the idle adjustment. the screw on the left must be the mixture adjustment. What is the best procedure for adjusting the mixture? I am familiar with the rich/lean pin adjustment on the barrel as well. It is the same on this carb as on the standard one. This carb just has 5 slots on the pin instead of 4.
 

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BoltsMissing

Active Member
Joined
Jan 31, 2008
Messages
897
Thanks for the pics, appreciated.


Beyond my comprehension though at this stage.
Mixture screw, Idle screw, some have choke adjust, but by the sounds of it, seems it has mixture screw AND pin adjust...,

I think this needs to be disected...,
 
S

SchwinnAlloySeven_GT5

Guest
I have had one of these carbs for over a year. Put 1600 miles on it, but removed recently because it needs a rebuild now. It's commonly referred to as a "CNS" and increases low-end torque significantly (nice with small sprockets!).

Adjusting the mixture via air screw takes a bit of trial-and-error. I screwed mine all the way in and then backed it out 1.5 turns, worked best for me. I did not adjust the pin setting.
 
Joined
Mar 16, 2008
Messages
688
I have always adjusted them by starting the engine, increaseing the idle, adjusting the mixture screw for highest engine speed, and then turning 1/2 turn in, so not to have lean condition.
 

Skyliner70cc

Active Member
Joined
Nov 17, 2007
Messages
1,344
Where does one BUY this carb and is rejetting needed? I had a Dellorto clone that worked great but the high speed jet was too rich for my altitude in Colorado.
 
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SchwinnAlloySeven_GT5

Guest
Rejetting may be necessary at high altitudes. But know this: if you live in a dusty area or ride off-road alot, the CNS carb will need a rebuild quicker than the stock one. It has 3 little ports that look like they require a vacuum hose on, but are supposed to be left open. This allows more tiny junk into the carb's sensitive parts.

I've tried capping mine but the carb didn't work right. I've also tried capping the troublesome fuel overflow hose and the carb didn't work right either. Closing the fuel tank valve is also more important with this one. The carb is vented and fuels moves quickly through it!
 
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andyinchville1

Guest
Hmmm interesting....I wonder if the little holes in the carb could have a hose attached to it and somehow run it to some nipples behind the air filter or maybe have a separate air filter for them (Like the PCV filters in cars)?...Might keep things cleaner for the carb that way...

Andrew
 
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