OMG I have to tune a CNS!!! Help

[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)