CNS Carburetor

Just my 2 cents worth, I like the CNS and found it to be an improvement over the NT style carb I ran before. I have not changed the jetting on it and it works nice. I may have lost a little on the bottom end, and I mean very little, but the bike runs much better and with no four stroking problems like I had with the NT. I never did mess with the jetting on the NT so my experience is stock verses stock. If someone wants to get rid of a CNS they are not using shot me an email.
 
sportscarpat said:
Just my 2 cents worth, I like the CNS and found it to be an improvement over the NT style carb I ran before. I have not changed the jetting on it and it works nice. I may have lost a little on the bottom end, and I mean very little, but the bike runs much better and with no four stroking problems like I had with the NT. I never did mess with the jetting on the NT so my experience is stock verses stock. If someone wants to get rid of a CNS they are not using shot me an email.
Click to expand...

You're runnin' stock exhaust right?
 
I was running stock exhaust with the baffle drilled, now I have the Grubee expansion pipe that's shaped like a banana. Best banana I ever bought. The CNS worked fine with the stock pipe. I guess I am one of the few but I have had good luck with the CNS. Couldn't imagine going back to the stock carbs now. Hope you figure yours out.
Pat
 
Finally got my CNS tuned to the point where it is ridable revs up to about 6500 I reckon and tops out a little under 30, I had to play with my expansion chamber, put the needle out of the nt carb in it, and put a bigger k&n air filter on it. I wish I could get Jets!!!
 

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I've had no trouble with mine either except for the filter getting saturated with oil. You can't tell when that has happened just by looking at it, it doesn't look any different. So it took me a week of fiddling around with EVERYTHING else on the engine to figure it out. Oh well live and learn. By the way, I'm not running a stock pipe either. It's my own version of the "poo poo pipe" made of electrical conduit with the stock muffler welded on the end. Works great and looks cool. ;)
 
Here's a question about these CNS carbs.
If that little barbed vacume port on top of the carb is for oil injection, could it cause a air leak if left uncapped?
I know the one on the bottom of the float bowl is a over flow & should be left open, but what about the two that are close together on top? what are they, & should they be capped off??
 
The barbed one(since no one has developed a oil injection system for them) should be capped off cuz its just a huge air leak. The two that are close together on top go straight into the float bowl and are vents that need to be open. I recommend running vent tubes off of them tho because rain flows right into the float bowl(learned this the hard way, note I don't have em capped off and the next day my moped ran like crap cuz of the rain).
 
I just put a inch long loop of hose on the two side by side vents with a small hole in the hose. The best solution would be to plumb them into the air filter like on real motorbikes.

I found mine to be very sensitive to the air cleaner, I ended up running it with the stainless steel mesh from a tea strainer and a half-airbox lined with foam rubber.

I made the airbox from a used 1l oil bottle. It is open at the front and zip tied to the frame tubes top and rear. It surrounds most of the carb and the foam soon gets oil soaked making an it an excellent dust collecter.
 
Hang on a sec the barbed fitting is on the outer venturi and is only an unfiltered hole not an actual leak. haha

wildemere i have found the same with the super sensitive inlet tract i have had to stick on a custom mesh filter since i fitted an expansion chamber.
 
Here's a update... I tuned the CNS carb in every way I possibly could & got it running as well as I could.
I told the owner of the bike to put the stock carb back on & see what happens & he says it runs way better with the stock carb?!?!
Not all engines like these carbs I guess... :-{
 
Venice Motor Bikes said:
Here's a update... I tuned the CNS carb in every way I possibly could & got it running as well as I could.
I told the owner of the bike to put the stock carb back on & see what happens & he says it runs way better with the stock carb?!?!
Not all engines like these carbs I guess... :-{
Click to expand...
Curious if it's a new carb or one that has been modified. Maybe it has a problem and somehow slipped through the stringent Chinese quality control!
 
UPDATE: got my CNS tuned in as good as I could and rode it around... then I got the leak of doom. (leaking around the drain) Also this carb doesn't have a neoprene tip so if it gets dirty it leaks. Combined with the vent holes, wrong jetting, and fuel leaking(also terrible millage).... I put the stock carb on with a SBP aftermarket air filter my bike runs way better... $50 down the drain... I tried as hard as I could to give this carb a second/third/fourth chance.
 
Looks like a couple people are unhappy with the CNS. I need a carb right now and wonder if its worth getting one of these problem carbs or just buying new. Sounds like a crap shoot to me.
 
Wow..! I just ordered a CNS from SpookyT today because I have three NT carbs that will not run right on my engine, I am hoping this carb will cure my problem by being adjustable to some point, the needles will not seal properly in any of the NT carbs I have when the engine is rev'd up, I can let the fuel bowl fill with gas and then shut the valve off at tank and the carb runs fine but they all will flood the engine down at high rev's, gas will start spitting out of the breather and the engine will choke down, I've set the float, lapped the needle and seat with toothpaste, the floats do not take on fuel, and they all idle pretty good, it's just when the engine is rev'd up and the vibration of the engine causes the needle to flutter and this allows the unwanted fuel to enter the bowl and wala....it floods down the engine. dont know why I have had so dang much trouble with these carbs but I have. got my fingers crossed and hoping the CNS will get me going...
 
Mapbike,
If three carbs have not cured your problem then it's probably not the carb. Make sure all your wiring is good, no lose connections, and clean your fuel filter.
 
I love this thread, "crap carb" no "its a great carb" "doesnt work properly" "works great"
"Fuels leaking"

If you cannot tune it propery it must be defective....right?

I wont boast mines the fastest mb with the CNS but it works great for me.

The biggest problem i have seen with this carb is alot of people have jumped from the nt to the cns, dellorto or what eva carb without any understanding of how the first 1 worked in the first place, oh its not working for me so im gettin the other 1, like the guy who tuned his cns carb by just idleing, yeh that sound about right sweeet.
You cannot just screw the idle screw in 2 1/2 turnes jet this big and needle on the second notch, she dont roll like that there are numerous things to consider elevation, temp, fuel octain, oil ratio, size of your airfilter etc etc.
Anyone contemplating a different carb should first ask themselves do i really know how this 1 works and will i know how a slightly more complicated 1 will work?
 
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