New engine!!! Running but dies when I use the clutch!!

Mine fresh out of the box in late May or June ran only if I had the choke on from partial to all the way. Wouldn't run right without it. After I pulled the black vent tube out of the back of the carb it ran beautiful!! Put a weedwacker fuel filter on the end if the vent tube and duct taped the hole shut on the carb and let it be.

Have you done that yet? If not go ahead and pull it then see if it starts and runs.

Whew - big fun ahead smemo.

First, you probably have air leaks around that white spacer bit. Just the way it is, I'd put cash money on it.

Second, after you figure out your air leak, tighten the jets. There are two jets - one is pilot which adjusts idle, the other is the main jet.

Third, don't use the choke. It's UNNECESSARY and will only complicate how you're thinking.

Fourth, forget all the quick easy ghetto fixes - you have an air leak. Solve that, be it with silicone, gaskets, grommets, pvc, brass, however.

Fifth, I don't like how you had to lean the mix - you shouldn't run less than 24:1 on break in.

Lastly, your clutch probably isn't disengaging all the way, so adjust the flower nut to allow it to disengage completely when you pull the lever. Don't do this first, do this last after air leaks are gone.

Whoa there duct tape goat. Your name implies ghetto fixes doesn't it?

All I was doing was relaying what others have experienced with these new 2010 motors and CNS carbs. Lots of wasted time when all that was needed was simply the fix I stated.

Now if we could use duct tape to fix the cheap chains these come with...That would be something. Almost as fun as the Mythbusters duct tape episode.

No, my name actually is the name of my death metal project.

6cyl - when you have an air leak, you fix the air leak, you don't pull a black 90 degree tube out. That really doesn't do anything at all. The only purpose of the black hose is to filter the air coming in as that black hose is for the air fuel mix on the idle - the screws ONLY affect idle.

Then why did the motor completely change when I pulled the line out and blocked the hole on the carb? Everything I did before to address any air leaks had no change whatsoever on how it ran. I'm not trying to be cocky or mean I'm asking since it worked for me.

October build date on label.
48cc w/ CNS carb and everything right out of the box other than chain.

All you did was disable the pilot jet's air intake, which adjusts your idle. Without that, you adjust your idle via throttle cable tension. Like I said, at wide open throttle, it's not going to make any difference. Loose jets, maladjusted floats, improper choking and air leaks are the major issues with the CNSv2/GenB carb.

Let me ask you 6cyl - have you adjusted the needle clip? Where on that needle is the clip? As well, do you bog anywhere throughout the RPM range? Do you have any loss of power or times of unresponsiveness?


These carbs are really great and can outperform the NT carbs when they're running right. You should have power all across the band, perfect response all the time, and never bog.

If your throttle is not as responsive as it should be, you've got air leak problems. If you have set your needle clip to run richer than normal, you're adding fuel to too much air, not the right solution. The correct solution is reducing the amount of air by solving the air leak issue.

If you're bogging at mid to high range RPM, you've got loose jets and/or maladjusted floats.

If you have to choke it to keep it running, stop it, you'll confuse yourself. Leave it alone. It's not a problem or a solution to anything except a winter start.

I haven't had anything apart yet. I read and read and read on these forums before I turned a wrench. Figured before I start adjusting everything start with the easiest and work thru what works and what doesn't. Read others were seeing a huge change with it so... I was about to tear into the carb and make some adjustments but figured what the heck and pulled the vent tube out. Starts great with barely any choke. Doesn't bog unless I nail it right after starting. Accelerates fine to WOT. I don't understand it either but maybe I'll find something when I start to adjust things next week. I will be done with break-in fuel/oil mix.

Never listened to deathmetal until I got older. Wife hates it. Sometimes it what I need. Ever see Metalocolypse on late night swim?

I'm glad you got things working better. I have been very lucky so far with mine in that it ran great after that little fix. I know there is more power in it ( hopefully 30+ mph) but I don't want to tune twice and I have a few miles to go before break in gallon is done. Read read and read some more and these guys will get u there.

Good luck!!