OMG I have to tune a CNS!!! Help

I have just installed my first CNS carburetor and found it to not have any mid-range power. I really appreciate all the advice you guys have put out here. First I didn't use the plastic shim that came with the carb. It doesn't seal on the intake. Instead I used the CNC intake from Manic Mechanic. It's made to fit the carb very well. The one thing I noticed is the new intake doesn't allow the carb to be mounted level. Is this a problem?
I haven't tried to make any of the suggested modifications to the carb yet but will as soon as I can. Does anyone have any suggestions for replacing the stock air cleaner? Stock air cleaner seems to not breathe very well.
 
It seems like a lot of people totally don't understand the plastic shim. It has nothing to do will sealing the intake. All it does is make the carb fit the manifold. All the sealing is performed by the O-ring on the end of the manifold. It it leaks, you probably don't have the carb pushed onto the manifold far enough.

I didn't have any problems getting the carb to seal, and I didn't use any sealer.
 
biknut said:
This is how I made the final adjustment,

There's a seam in roughly the center of the plastic float. I adjusted the float till the seam was parallel to the sealing surface of the float bowl.

Compared to stock, this made the fuel level slightly higher in the bowl.
Click to expand...

Is this adjustment with the needle depressed or just where the float touches the needle?
 
Sanction said:
Is this adjustment with the needle depressed or just where the float touches the needle?
Click to expand...

The needle is on it's seat, and the float is just resting it. These float needles don't have a spring in them like most float needles do. It's just a solid piece..
 
I just removed the tube from breather to bowl. It's as if my engine has suddenly come alive. I can't thank you enough. I had already ordered a new NT Carb. to replace this on. I think I'll go ahead and get it just to be safe. Removing the tube from the bowl to breather has me smiling again.
 
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biknut said:
The needle is on it's seat, and the float is just resting it. These float needles don't have a spring in them like most float needles do. It's just a solid piece..
Click to expand...

Mine has a spring loaded needle valve. I would assume then parallel with the needle pressed in.
 
ok so i pulled the hose on the outside of the carb that goes thru the back side of it and used duct tape to close it off and it runs great. left the other end of the hose connected to the nipple and with engine running held my finger over it and no difference that i could tell. no bogging like before and barely used choke at all. before i pulled the hose i had to work the choke to varying degrees throughout acceleration to top end. I thought i was going to have a helluva time tuning this thing but it's fine now.

can anyone tell me what that hose is/was doing? was it just put there to keep crap out of it during shipping? i read something about it awhile back but memory...
 
That hose is the vent, do not cap it off either leave the hose open or use a small engine gas filter as I did. I have tried clsing it off and no fuel would flow into the carb. This is a EPA idea that doesn't work on some engines, they didn't want fumes venting to the air.
 
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Thanks guys. Very much appreciated. Wanted to swap a different fuel filter from tank anyways. Guess I'll buy 2.

Amazing how well this thing runs now.
 
Wow!! Shocking!! Yup, checking spark plugs. ran it and for a bit then pulled spark plug wire off spark plug since my kill switch doesn't kill anything. WOW!! Never thought I'd ever get spark all the way up to the family jewels. Thought I was on an episode of Jackass or something. Don't think I will ever do that again. Although I have a few friends I'd like to see if we can duplicate it with :)

Good news was that spark plug looks great!!
 
I did that once on my Briggs powered mini bike. The little metal flipper to stop the engine on the cylinder head flew off, so I just yanked the spark plug wire off the spark plug.
Lit me up until the engine came to a stop. I could not let go of it, my muscles just tensed up. I went inside and laid down for a 1/2 hour to let the pain subside. After that I immediately re-installed the metal flipper.

Alternate ways to kill an HT engine:
At idle speed either let the clutch out while holding the rear brake on, or turn on the choke to drown the spark plug.
 
i just picked up a weedwacker gas filter and a little bit of fuel line. should work quite well to protect from weather and still let it breathe. i figure a zip tie would keep everything in place too. i'll install in a bit but i need to stop sweating first. very humid today and i've been running around non-stop today.
 
I just find it strange that on some if you pull the vent tube out of the air intake they run better, and some have no change. Is there such a difference from Carb to Carb?
 
Sanction said:
I just find it strange that on some if you pull the vent tube out of the air intake they run better, and some have no change. Is there such a difference from Carb to Carb?
Click to expand...

The only way removing the vent tube could make any difference is if it was pinched to start with. It's just a vent tube to the float bowl. It really doesn't matter if it's vented to the air cleaner, or the atmosphere. It's not like it's a crankcase vent, or something like that going into the air cleaner.
 
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