Inside the 2010 Grubee Skyhawk CNS Carb

[CruisinOCMD]

Superbob I hear you man. I tried everything i could think of as well and even used the standard VW procedure that always seems to work on my Corrado (I hit it with a hammer) and still nothing out of this carb.

My solution - I said screw it and bought an NT carb Motorized Bicycles Gas Bike Engines Gas Powered Bikes Motorized Bicycle Parts she runs like a champ now! Even with the smaller components and jets my GT5 Super rat is ripping at 35+ without breaking a sweat. Personally like the NT carb better all around, the air cleaner looks like a black skull which goes well with my Matte black cruiser in stead of the pinkish red one. The choke lever is small and is mounted directly to the carb so it cleans up the look of the bike and one less cable to run, and best of all IT WORKS!

Good luck with the bare foot welding man

 

[Radfletcher]

Hi, I guess I just want to toss this out there, While we're on the subject, that if anybody out there has a couple old NT carbs kickin' around in their shop, that they aren't using, I would happily take one of 'em off yer hands... I'll kick a few bucks your way. or we could trade! I have a hardly used 2010 CNS carb. (not a joke, btw. I'm serious, promise!)

 

[surfishjoe]

Hi, newbie here. I built a bike with the 2010 grubee kit and have had problems with the CNS carb as well. However, I have been learning a lot from this site and have my bike running pretty decent. First thing i did was replace the flakey white washer with thick rubber. This helped but was not great. Only lasted a little while before it would leak. I bucked up and got the Pirate large CNS intake and she runs much better. The carb fits tightly on the intake tube and doesnt move. I hit 33 mph the other day and have full throtle response with no need to ever hit the choke. It only likes to run with the clip on the bottom setting. I am in the process of dialing it in now and will be putting in a fresh plug soon. Is it normal for the carb to drip a little fuel out of the drain/vent tube on the bottom of the carb. It is not much more than enough to leave a little sheen on the frame and doesn't drip whenbeing stored. Thanks for all the info!

 

[sohcahtoa]

Thanks for this thread, everyone. Finally got my bike up and running this week, and have many of the same issues reported here with the 2010 CNS carb... Just glad I now have a better understanding of what's going on and how to try tuning it

 

[KCvale]

Is it normal for the carb to drip a little fuel out of the drain/vent tube on the bottom of the carb. It is not much more than enough to leave a little sheen on the frame and doesn't drip when being stored. Thanks for all the info!

You mention using a straight intake, that puts the carb at a pretty good angle.

Two things can happen then.
1. The gas flow needle doesn't slide all up all the way closed from side friction and leaking.
2. The float wasn't lowered to compensate for the steeper angle.

You can fix the latter buy lowering your float level a touch by gently bending the tab on the float cross bar away from the float just a touch!.

A quicker fix for both is just turn the carbs gas valve off 60 seconds before you turn the motor off.
You will still most likely get some overflow in the tube, I face mine up to tell right away if I have the float level set right, I can see the gas in the tube.

 

[surfishjoe]

Hi guys here is an update on my CNS carb. I broke it. Bike was running half decent when i noticed it was a little loose on the intake tube. I tightened up the screw that clamps the neck of the carb onto the tube and , snap = the actual carb body broke. Looks like I will be ordering an NT carb for 20 bucks. Ill let you know how it compares.

 

[Frankenstien Bikes]

KCVale,

my CNS carb has issues too, thanks for all the info. My engine idles great, but like mentioned by others it boggs and wants to die at WOT, so ill try the black silicone technique and see if that helps. U recomend I mess with the clip notches, forgot what that pacman thing is?

 

[Frankenstien Bikes]

Just an update while I have minute...

THIS WORKS

The MAIN problem with these carbs is the rubber gasket doesn't go past the big grove for tightening the carb on.

So what I did was fill in all the gaps with some gas resident sealer.

Nothing on the inside, just the gaps in the carb body and the gap in the plastic spacer ring.

So anyone else try sealing up your intake like this with great results?

Pushed the carb on tight, torqued it down good, and then sealed the outside at the intake manifold once it was mounted too.

She runs like a charm now.

One more note...
Check that your carb came with a gasket between the carb body and the inside of the cable cover plate.
I have one sitting here that shipped new without one.

So anyone else try this and have great results?

 

[Greg58]

I solved this problem by making the spacer out of copper.

 

[KCvale]

Three things to note...

1. The C-32CNS66 carb is for 66cc motors.
I have never been able to make that 66cc carb run on a 48cc motor, even with an expansion chamber. The air sealing technique has however made the carbs work great on 66cc motors.

2. There is an elusive C-32CNS48 carb that (I assume) is supposed to go with the 48cc motors, seen a pic of one but can't recall if I ever used one back in the early days.

3. There is now a 2011 C-32CNS66 carb, seen one, the rubber gasket is now wide enough to cover the gap, and the spacer is rubber as well.
The local guy that built it sold it, but it seemed to run great without intervention.

If you have a 48cc motor and want to change carbs, try to find a Speed carb, not the ancient NT if possible. They perform better and the carbs gas shut-off valve alone is worth the extra $5.

Pac-Man clip:

This is for adjusting fuel/air mixture under throttle.
The farther down the needle towards the pointed end, the more fuel to the given air volume making it richer in relation to how open the throttle is.

Too rich and you waste fuel and gum up your plug.
Too lean and it runs too hot.

Hope that helps.

 

[Frankenstien Bikes]

Three things to note...

1. The C-32CNS66 carb is for 66cc motors.
I have never been able to make that 66cc carb run on a 48cc motor, even with an expansion chamber. The air sealing technique has however made the carbs work great on 66cc motors.

2. There is an elusive C-32CNS48 carb that (I assume) is supposed to go with the 48cc motors, seen a pic of one but can't recall if I ever used one back in the early days.

3. There is now a 2011 C-32CNS66 carb, seen one, the rubber gasket is now wide enough to cover the gap, and the spacer is rubber as well.
The local guy that built it sold it, but it seemed to run great without intervention.

If you have a 48cc motor and want to change carbs, try to find a Speed carb, not the ancient NT if possible. They perform better and the carbs gas shut-off valve alone is worth the extra $5.

Pac-Man clip:

This is for adjusting fuel/air mixture under throttle.
The farther down the needle towards the pointed end, the more fuel to the given air volume making it richer in relation to how open the throttle is.

Too rich and you waste fuel and gum up your plug.
Too lean and it runs too hot.

Hope that helps.

Thanks alot, I have the 66cc Super Rat, and the C-32CNS66-EPA CARB. Did the silicone technique last night and will see if that fixes my prob this evening when I get home from wrk.

 

[Frankenstien Bikes]

Im also running a K&N style air filter and Expansion Chamber by SkyHawk.

 

[Greg58]

This may be a mis box but all 6 of the engine kits we have installed came with the C-32CNS66-EPA carb

48cc grubee angle fire 2010

 

[Frankenstien Bikes]

Forgot to mention, I also have a 2011 Grubee SkyHawk Gt5 slant head I picked up for a friend, ill check out that carb and see if it has the wider rubber seal and see if the second plastic seal is changed to rubber. Cause I have a 2010CNS carb on my super rat and can compare the two.

 

[Frankenstien Bikes]

Well with silicone its still bogging, pulled the plug and its dark oily look. So its not running lean, its also in the break in stage, runs good going down hill but any load on slight up hill it dies with the more throttle i give it. I moved the Pacman clip down a notch seemed to run a bit better but still boggs, Ive about had it with this carb........

 

[Greg58]

Try pulling the vent tube off, it helped me but may not help you. Did your k/n filter come pre-oiled mine did not after I oiled it the bogging stoped.

 

[KCvale]

Well with silicone its still bogging, pulled the plug and its dark oily look...
I moved the Pacman clip down a notch...

Just so we are on the same page, you run the motor WOT and while still holding the throttle open you push and hold the kill button until it dies, then check the plug.

Dark and wet is too rich.
Moving the clip down makes it even richer.
Try putting your clip clear at the top and check.

 

[Frankenstien Bikes]

Just so we are on the same page, you run the motor WOT and while still holding the throttle open you push and hold the kill button until it dies, then check the plug.

Dark and wet is too rich.
Moving the clip down makes it even richer.
Try putting your clip clear at the top and check.

Thanks, no I pulled the plug after I rode.
so I should start the engine, then with no load rev it up, then hold it WOT, hit the kill button till it dies then check plug correct?

 

[Frankenstien Bikes]

Try pulling the vent tube off, it helped me but may not help you. Did your k/n filter come pre-oiled mine did not after I oiled it the bogging stoped.

K, thanks ill try this too, ordered the filter from sick bike parts, so thoght it came pre oiled.

 

[Frankenstien Bikes]

So I talked to a tech who owns a motorized bike shop out here in california where im from, and he sells the gt5 with the cns carbs. He said in order for the carbs to run right u need the bigger jet, of your running the K&N style air filter, and to keep the pacman clip in stock position. Gonna get the bigger jet, ill keep u all posted.