New High Performance CNS Carburetor Gen B
- Thread starter GothTech
- Start date
Tell us more about you engine, 66 or 48 cc and what fuel mix ratio. There are a lot of us using the cns2.
On the cns2 there are three stages of adjustments, the two screws control the idle. 2 the e-clip will adjust the mixture from about 20% to 80% throttle open. 3 the size of the main jet controls wide open. From what you have posted you need to try adjusting the clip on the needle, there are five notches with the top being the leanest. You may see some improvement by trying different notches. If you have to adjust the main jet BIKNUT has a good post on his tuning.
http://motorbicycling.com/f34/omg-i-have-tune-cns-help-30169.html
http://motorbicycling.com/f34/omg-i-have-tune-cns-help-30169.html
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I have a cns too.I have a 48cc grubee sky hawk gt2b motor kit.The problem I'm getting is bogging at quarter throttle,now Idle is great and take off is good but a quarter throttle sucks.I checked for air leaks and can find any.I heard adjusting the e clip,adjusting float and drilling jets I really don't want to drill the jets.so what spot should I adjust the e clip if that's what you suggest...thanks a bunch
I have found on some 48cc engines with the cns2 if you remove the vent tube it will solve the bogg, it's not hard to do just pull the small hose out of the back of the air filter base and cover the hole with tape to keep out debris and go for a ride. do not close off the vent tube it must stay open so fuel can flow into the carb. The improvement on mine was like i changed carbs.
make sure there are no air leaks, seal it up good, pull the line that runs to the air cleaner and plug it, make sure the head bolts are at proper torque
with it at idle spray starter fluid around where the carb connects to the intake, under the carb at the engine block and around the intake where it bolts to the head, if the moter slows or quits you have an air leak.
Lou
here is a link to what I did, I wrote it a few days ago....
http://motorbicycling.com/f51/first-bike-33026.html
with it at idle spray starter fluid around where the carb connects to the intake, under the carb at the engine block and around the intake where it bolts to the head, if the moter slows or quits you have an air leak.
Lou
here is a link to what I did, I wrote it a few days ago....
http://motorbicycling.com/f51/first-bike-33026.html
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no it does not, it looks like it should but the bowl will not fill with the vent tube caped off.
i beg to differ (whatever that archaic saying means.)
i finally found time to mess with these stupid carbs, and i soldered the vent tube on the outside of the carb and the overflow tube in the float bowl closed.
it works perfect. solid acceleration all the way through.
here's my common sense reasoning behind it:
the carb shouldn't need to vent, nor should it overflow. the gas cap on the tank should take care of venting, and the float should shut the gas off so it won't overflow. that's basic carburator technology.
while riding, gas is limited by the throttle, the jets, the float, and shouldn't be overwhelmed by gravity, so any overflow tube isn't needed. if it overflowed while riding, it shouldn't run.
when parked, the petcock should always be off, so the gravity can't overwhelm the needle and seat and flood into your carb. if for some reason you didn't have a petcock, overflow tube or not, gas would just start pouring out.
that reasoning makes the overflow tube completely useless.
i'm also running the clip on the first notch. i haven't checked the plug yet as it's only been run for 30 minutes on a brand new engine, but i think the cns carb is too big for the engine, and floods it out, so a leaner mixture is required.
after a few more runs, i'll post up more results. you might wanna wait till then before soldering anything closed...
i finally found time to mess with these stupid carbs, and i soldered the vent tube on the outside of the carb and the overflow tube in the float bowl closed.
it works perfect. solid acceleration all the way through.
here's my common sense reasoning behind it:
the carb shouldn't need to vent, nor should it overflow. the gas cap on the tank should take care of venting, and the float should shut the gas off so it won't overflow. that's basic carburator technology.
while riding, gas is limited by the throttle, the jets, the float, and shouldn't be overwhelmed by gravity, so any overflow tube isn't needed. if it overflowed while riding, it shouldn't run.
when parked, the petcock should always be off, so the gravity can't overwhelm the needle and seat and flood into your carb. if for some reason you didn't have a petcock, overflow tube or not, gas would just start pouring out.
that reasoning makes the overflow tube completely useless.
i'm also running the clip on the first notch. i haven't checked the plug yet as it's only been run for 30 minutes on a brand new engine, but i think the cns carb is too big for the engine, and floods it out, so a leaner mixture is required.
after a few more runs, i'll post up more results. you might wanna wait till then before soldering anything closed...
Baird I used my engineering degree from spu to figure this out,( seat of the pants) I caped off the vent and started down the road 1/2 mile away the bike ran out of fuel I pulled off the cap and it started up . The only thing I did was cap the vent, all carbs I have ever worked on have a vent be it a holley edelbrock ford. The size of the vent is allways bigger than the incoming fuel flow. The overflow is below the level of the intake to keep fuel out of the engine in case the needle gets stuck open by debris. SAFETY FIRST!
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