OMG I have to tune a CNS!!! Help

[nightcruiser]

Sounds like you went too lean when it would only run with the choke on... The spacer can be made from a section of PVC pipe for about $1, there is a post in the thread I created about tuning my CNS carb where I detail what I used and how I made my spacer. Check out that thread here....
http://motorbicycling.com/showthread.php?t=32736&highlight=cns+carb+working+great

JB weld on a carb is not a good idea IMHO, you need to be able to remove the carb, not have it permanently attached. The rubber seal in the throat of the carb fits perfectly on the end of the intake and makes a great seal when installed properly (again, read thread linked above). Someone has also detailed how to make the spacer out of copper, but the one I made from PVC water pipe is virtually indestructible, I tried to break it and couldnt....

IF you are lowering the float but still get gas out of the overflow then you have a problem with your needle valve, it is not closing. You need to check it to make sure there is no debris stuck in there preventing it from closing and make sure you put the pointed side of the needle in to the valve. You can check the operation of the needle valve by turning your (clean) carb upside down and blowing through the fuel line. (more details in the post linked above.

I rode the he11 out of mine yesterday, I am extremely happy with how she runs, pulls like he11 from barely rolling right up to top RPM.

 

[nightcruiser]

Another thought...
When you pull the bowl make note of where the overflow tube is connected, see that inside the bowl it is connected to a riser tube. The fuel level must reach the top of this tube before it can come out of the overflow.....
If you are getting fuel out of the overflow even when the fuel level in the bowl is low then perhaps this overflow riser tube is not properly seated in the bowl, or perhaps it is defective in some manner (a hole/crack in it) This is not common, but could happen, the fuel inlet nipple wasn't firmly pressed in place on my carb, couple taps and it was all fixed.
Just thought I would throw that out there....

 

[locell]

This is Duchess. A beautiful silver blue Micargi-Rover beach cruiser, with a silver Grubee SkyHawk 80. It's only a few hours old now, and has been around the block for about 3 miles so far. It belongs to my friend Corinne.

http://www.youtube.com/watch?v=dXysa1FNzEs


I really like the chain tensioner on this, it is attached at both ends to the frame?

 

[biknut]

This is Duchess. A beautiful silver blue Micargi-Rover beach cruiser, with a silver Grubee SkyHawk 80. It's only a few hours old now, and has been around the block for about 3 miles so far. It belongs to my friend Corinne.

http://www.youtube.com/watch?v=dXysa1FNzEs


I really like the chain tensioner on this, it is attached at both ends to the frame?

Yes it is, with conduit clamps. 2 at the top, and one at the bottom. I done the same thing on 4 different bikes without any problems.

 

[Garrett66]

I've got a CNS acrb of my grubee and this is my first bike build. I don't have much experience, but it seems that no fuel/air mix is making its way into the compression chamber. Any suggestions

 

[rustycase]

I've got a CNS acrb of my grubee and this is my first bike build. I don't have much experience, but it seems that no fuel/air mix is making its way into the compression chamber. Any suggestions

If such is the case, there is a liklihood your piston is not moving when the crankshaft rotates.
Even with little experience, I might guess you could notice that?

Is your throttle cable connected properly to the slide in the carb?

Is your petcock, filter, or needle valve plugged with gunk from a new tank?

Does your sparkplug get wet with unburned fuel when you pedal/crank the engine?

Perhaps you might try with/without the choke in the ON position...
IIRC, a cns uses a choke cable for an enrichen circuit. the cable runs up to a handlebar lever...
Perhaps you could try removing the air cleaner and holding a rag over the carb intake as someone spins the back wheel a bit for you... Please... do it with the sparkplug wire disconnected for this test!
There should be at least some gasoline dripping out the back of the carb after this short test...

Have you disconnected your white wire kill switch?

Might be a good idea to read through a bunch of the carb threads...
CNS just ain't my favorite, but they do work...

Good luck
rc

 

[nightcruiser]

I've got a CNS acrb of my grubee and this is my first bike build. I don't have much experience, but it seems that no fuel/air mix is making its way into the compression chamber. Any suggestions

Pull off your air filter, look in the carb and see if the slide is moving and opening the throat of your carb when you twist the throttle, if so your motor is at least getting air...

As the previous post stated, being a newbe nothing can be taken for granted. re: is your motor really turning over (do you have a clutch issue?), is the gas flowing in the fuel line etc.... Until you get your motor running disconnect the kill switch, sometimes they fail and get stuck in the kill position. Make sure the white wire is isolated and not touching anything, make sure no other wires are touching anything.

If you know your motor has been turning over and fuel has been flowing then pull your spark plug and inspect it. Does it still look new? (never fired) is it wet? (was getting fuel, possibly flooded) If its wet then let the clutch out so the motor will turn over and roll the bike around a little bit with the spark plug removed to blow out gas that may be in the cylinder, make sure no spark or flame is around to ignite any fuel that may come out of the spark plug hole. Then install the spare plug that came with your kit, or an NGK BP6HS or other upgrade plug. Make sure all parts are in order in the spark plug boot, make sure you've removed the cap from the spark plug (you should see a threaded stud on the top of the plug, not the snap on cap) make sure the plug boot is on the wire properly.... Ride to a decent speed, let the clutch out (should hear and feel the motor turning over and creating drag) continue pedaling and open the enrichment jet (choke) by pulling the cable with the lever.... she should start up.... Also, do yourself a favor and run an inline fuel filter....
Post back more details and we will try to help you more....

Edit: and your fuel mix should be something around 20:1 or 24:1 for the first two gallons during break-in. I did 20:1 for the first gal, 24:1 for the second, and 32:1 thereafter with conventional 2-stroke oil (not marine type)