help with cns carb

The screw in the center is idle , screw it in for higher idle , out for lower idle.

The screw on the left is air/fuel mix. In for less air , out for more air. I have mine at 1 complete turn out from fully screwed in.
 
No. By screwing the air/fuel screw in you make the fuel to air mixture rich. Meaning more fuel then air. Screwing it out leans the mixture. Meaning more air then fuel. Its a fine line to make it perfect. To far in (rich) and you will foul plugs and the engine will be boggy. To far out (lean) and the engine burns hotter and that can burn it up , warp stuff , etc. Its always better to be a touch on the rich side then the lean side.

From the posts Ive read the sweet spot on the mixture screw is 1 to 1.5 turns out from all the way in.

:)
 
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ok i will do that thank you root i appreciate it, how its setup right now it runs better with the choke on, what is that caused from? im sorry to ask so many questions but i want to learn the proper way of gitting my bike to run right and understand
 
If it runs better with the choke on its getting to much air. Its running lean. The screw is too far out. Screw the mixture screw in a quarter turn and see how it runs. Repeat till it runs better.

When you think you have it right , slap in a new plug , ride it around for a couple miles. Pull the plug. White = too hot , lean. Black and gooey = fouled , too rich. Light brown = money.

Also make sure to mix your gas at 32:1 or 4 ounces of 2 stroke oil to 1 gallon of gas.


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sorry for the silly question but when we are looking for the brown plug. should the little prongs be dry or wet. my plug is brown but pretty dry. before messing with the carb it was black and oily.
 
driftology said:
sorry for the silly question but when we are looking for the brown plug. should the little prongs be dry or wet. my plug is brown but pretty dry. before messing with the carb it was black and oily.
Click to expand...

Brown and dry is good.

Black and oily: too rich
 
I just delivered a bike today and ended up putting an old speed carb on it because I could never get it to accelerate on the street with the CNS. I tried five different main jets (2 leaner and 2 richer), all of the needle settings with each jet with absolutly no success. I did not play with the mixture screw that much though. Isn't that just an idle mixture screw? How much does it effect mid to WOT? Only good thing to come of this so far is I have 2 CNS carbs to fight with for the last kit I have in stock.
 
A little late here. Are you just breaking the bike in? I recelty got a 50cc kit with cns carb that would run somewhat poorly I was dissappointd. I messed with the air mixture and idle to get it running as best I could. I was going to to mess with the carbs but my father said just take it easy for awhile and that the rich oil to gas ratio may have something to do with. After about 30 miles runs great like a completley different bike. Just my experience good luck
 
Getting the air mixture screw in the right position seems to be essential. The position of the pac-man clip seems to be more about fine tuning the engine. People have complained about the bore size of the main jet being too big, but it's a difficult to say if the ideal jet size should be smaller. Giving up on the CNS carb seems premature.
 
Mine (CNS V2 with MM manifold and AFAIK the stock jet) is running strong with a nice brown plug, but the idle speed is a little too high when the motor is cold and low enough to stall when it's warm. Both adjustment screws could use a dab of something on the threads--they feel awfully loose.

I've ordered an NT "speed" carb just to see if it makes a difference, but I don't think there's anything really wrong with my CNS.
 
Maybe. The MM manifold makes a much better seal than the stock one with the cheesy plastic ring, but there are other places that could leak. When I get the speed carb installed I'll replace the gaskets with the ones from the CNS rebuild kit and see if that makes a difference.

It looks like I'm still running a little rich, since it's four-stroking at higher RPMs (anything above 35 MPH).
 
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