First build, no idle, 4 stroking, etc.

[Tippyman]

Just finished the install on my first bike and went for a short ride. Occasionally will have good power at 3/4 to full throttle, but with the choke off it runs like crap.

The engine also will not idle at all. Unless I'm going pretty fast it just wont stay running. It's dead the second I put the clutch in.

The whole "choke on/runs better" led me to believe its an intake leak. (ie. only runs good with alot of fuel.) I took the manifold off and put Honda-Bond on the intake gasket. When I went to tighten it back down, I noticed the studs were loose. I removed them completely and used bolts instead. i was hoping this would solve my problem, but it seems I have the opposite problem now.

It's constantly four stroking, and if the choke is on it will barely run or move. It will run poorly with occasional normal 2-stroking until the upper rpms with the choke off.

Still no idle...

 

[killercanuck]

Definitely sounds like an air leak, do you have an O-ring where your carb seats onto the intake manifold? Alot of air will get in if theirs not, from those pesky grooves on the carb flange. Try wrapping it with plumbers(or electrical) tape to see if that fixes it. If it does, you'll probably need an O-ring(or leave the tape, but that'll look crappy, eh).

That's a start anyway, an expert will be along eventually with more advice, I just happened to be here.

gl.

 

[Tippyman]

BTW: I have a 2010 Grubee kit with the new CNS carb.


I just removed the air filter and it runs 100% better. No 4-stroking, clean power-band, nice top end.

Still not idle. Put the clutch in, it'll put put put four or five times then die.

Put the air filter back on, runs like ass and still won't idle. I was literally riding around with it in my hand putting in on and off while riding.

 

[Tippyman]

It randomly idled for like 10 seconds one time, now it won't do it again.

Still doing the air filter thing...

AAARGGHH!!!!

 

[Kevlarr]

Where's the clip set on the carb needle? Sounds awfully strange that the air filter is causing it to choke out.

 

[GearNut]

It also sounds like the idle speed is set too low.

 

[Tippyman]

It's the new CNS carb, from what I've seen, no one really has alot of experience with it. The idle screw won't move, it's glued in place. Turning it in supposedly raises the idle, but the screw seems pretty much all the way in anyway.

 

[GearNut]

Just to clarify that we are talking about the same screw here;the screw near the center of the carb, not the one closer to the air cleaner, right?

 

[Tippyman]

The one closest to the air filter is the mix screw. I messed with it to no avail. The idle screw will not budge, but when compared to the mix screw it's pretty much all the way in anyway, which is what I would want for a higher idle.

 

[GearNut]

Ok, we are talking about the same screw then.
I am still flabbergasted that the air cleaner would be so restrictive.
The "choke" on that carburetor is actually an enrichner circuit.
The cable lifts up a plunger which uncovers a separate fuel circuit to add fuel to the intake charge. Is the plunger on yours sealing properly when you turn the choke lever to the off position? I fit does not close completely then the choke is always in the on position.
Even if it is only slightly leaking it could wreak havoc in the air/ fuel ratio, making it too rich.

 

[GearNut]

Try removing the cable from it and reinstalling the plunger and return spring only.
Also, there is a black rubber seal on the end of the plunger. Is it deformed in any way?

 

[Tippyman]

Where would I look to see this? Remove the air filter and peer in the carb inlet? I feel like the choke works because of the difference in the ride quality while using it mid-flight.

 

[Tippyman]

Try removing the cable from it and reinstalling the plunger and return spring only.

Would this simulate the choke always being on or off?

UPDATE: Just went out to look at the choke situation and fiddle with some other stuff. Decided to check how the mixture looks on the plug. The plug was only finger tight! I just unscrewed it by hand. Might be a point of concern, no?

Anyway, the plug looked OK I guess, dark chocolate & oily on the electrode.

I went ahead and put the spare plug that came with the kit in with some anti-seize. Can't test until tomorrow since it's dark. (Time to get a 6v light? )

 

[killercanuck]

Oh, its a CNS? Do you have the proper hose clamped, and the other one vented? There's supposed to be one hose clamped off, and one left open(but lined to below the carb, for some reason)
Check out this thread for some more info:
http://motorbicycling.com/f34/new-cns-carby-what-vent-tube-4604.html

and search "CNS Venting" on our "top of the page Google search", lots of threads will come up. If you have the hoses wrong, it can cause your problems. (from what I skimmed through)

gl.

 

[GearNut]

You can only look at the enrichner plunger after removing the carburetor top cap. There are 2 screws holding it on. There is a gasket between the carburetor body and top cap.
Be ready for the spring pressure of the slide return spring and enrichner return spring to push up on the cap as you are removing the screws. It will make it easier if you push down on the cap as you remove both screws. Do not worry, there is nothing in there that should fly out across the room.
You will have to compress the spring away from the enrichner plunger enough to slip the end of the cable out of the hole in the plunger. It is different than a slide, actually easier.

 

[GearNut]

By the way, the CNS carburetor is actually a moped carburetor. I have rebuilt many of them when I was younger. It was years ago, but I remember them quite well.

 

[killercanuck]

Ey, I found this info:

the cns carb settings are as follows , and i have found to be the best setup

the bottom tube is overflow for have a tube on it running downward
the 2 tubes side by side , plug the left one and run a tube on the right one as a vent
the top one on the other side with the barbs on it run a tube on it as a vent

for the idle screws ,
left screw is your air/gas mixture (in is less air)
right screw is your idle speed (in is speeding it up.

hope this helps

That is from this thread, post #3:
http://motorbicycling.com/f13/cns-carb-adjustment-20461.html


Edit, Sorry GearNut, I thought he should know about the right venting/downtubes, etc... Just in Case, eh?

 

[Tippyman]

Ey, I found this info:


That is from this thread, post #3:
http://motorbicycling.com/f13/cns-carb-adjustment-20461.html


Edit, Sorry GearNut, I thought he should know about the right venting/downtubes, etc... Just in Case, eh?

I tried that method and didn't have good results. The only way mine will run right (and I'm using that term loosely) is if I connect the bottom nipple (fuel vent) to the top nipple (oil inject).

 

[GearNut]

Connecting the hose in this manner would cause a slight vacuum to be created in the fuel/ float chamber which in turn would reduce the volume of fuel flowing through the main fuel circuit, resulting in leaning out the air/ fuel mixture.
I really think that you are fighting a rich air/ fuel ratio problem.

 

[Tippyman]

Connecting the hose in this manner would cause a slight vacuum to be created in the fuel/ float chamber which in turn would reduce the volume of fuel flowing through the main fuel circuit, resulting in leaning out the air/ fuel mixture.
I really think that you are fighting a rich air/ fuel ratio problem.

Well damn...

Guess I'll check out that choke stuff you were describing.