I wanted to start a new thread here on the CNS carb, cause most of the threads are about problems, bogging, broken spacers etc. I have been through a couple week crash coarse on the CNS card and just recently got mine running super sweet, so I figured I a CNS carb success thread was in order....
First some background. I got a new Grubee SkyHawk GT-5 66cc kit this spring, it was a fresh kit dated 04-20-2011 with the newest CNS carb (C-32CNS66-EPA). After assembling I had a hard time getting her running, didnt know what to expect, eventually got her fired up after I realized it was going to take a lot of throttle to make her fire. I couldn't get idle unless I held in the throttle, once I had her rolling I could get a pretty good top end speed but never could get her to idle and slow riding was extremely rough.
I did a LOT of reading of forums etc, tried pulling the vent tube etc, I couldn't find the magic bullet to make this thing run. In the end it took a couple adjustments to get it running right. I waited until I went through the first two gallons of break in gas and moved on to my standard mix (32:1) before I bothered digging into tuning the carb cause I know the mix is going to effect everything.
The first problem with the carb was discovered accidentally. I had hopped on the bike and started riding without turning on the fuel. After running a bit the engine started running great all of the sudden, finally could almost get idle and I was getting better pull on the low end of the throttle. I was really happy, then she died... Failing to start her back up I quickly discovered the fuel valve was off. After turning on the fuel valve she started up but was running crappy again, no idle, dead throttle through most of the range etc. Connecting the dots to the fuel supply I turned off the fuel valve again and sure enough she started running sweet again for a short while then died. This behavior was consistently reproducible, so that got me thinking... Must be fuel level problem, so lets look at the float...
I was reluctant to open the carb on the new kit, I figured its new so it must be right. That's a bad assumption about anything to do with these china girl motor kits! When I finally decided to open up the carb I found it was no biggie. I also found that the screws holding the carb together were loose so I can only imagine it was one giant air leak, you should at very least check those screws before you install your new carb. Also, in the process of working on the carb the fuel inlet nipple fell off, I guess it wasn't pressed down far enough at the factory. Now I know where that little bit of fuel was coming from that would crop up every once in a while!
If you have the carb on the bike you should turn off the fuel and try to burn out as much fuel from the line and carb as possible before you remove it. After you remove the carb unscrew that one screw at the bottom of the bowl that has the red gasket behind it, that is the drain screw, the remaining gas will drain from the carb when the screw is out. Next flip the carb upside down and remove the four screws from the bowl and pull it off. You now have the carb opened up and are looking right at the float.
My next post will be about the float....
