My carb is perfectly level with the stock intake, but I'm ordering the large intake so I can get rid of the crappy plastic ring. I assume I'll be sacrificing my level carb with the new intake because it is straight. Hmmm... anyone using the large intake and at what incline do you have. Assuming your carb was straight to begin with. I ain't re mounting my engine. No way.
Inside the 2010 Grubee Skyhawk CNS Carb
- Thread starter KCvale
- Start date
Son of a gun...
I pulled the CNS off and pulled the white spacer out from the inside.
It looks like the rubber O ring was pretty tore up, most likely because of the tight fit I have to twist it to get to the top screws for cables before I can remove it.
Anyway, Iput black silicone sealant on the manifold, slid the white spacer on, filled it it's gap and coated it as well, then slid the carb on.
When I snugged it up I got a nice even bead squeeze out around intake and secured it.
It took off like a banshee, no bog at all.
I just can't believe the air seal is so poor on these things!
Anyway, I still need to mess with gear ratios but no sense in it until Monday, I have more parts coming from Sick Bikes...
Expansion Chamber - BLACK - Exhaust Pipe $67.95
Air Filter - Low Profile $13.95
Plug Wire - High Performance $6.49
NGK BPR6HIX - Spark Plug - Iridium $6.49
Sub-Total: $94.88
Zone Rates (Shipping to US : 15.95 lb(s)): $16.00
Total: $110.88
The whole motor kit only cost me $10 more than that!
With any luck, those upgrades will power the new aggressive shift table I programed. If so it's going to be a spooky fast ride ;-}
I pulled the CNS off and pulled the white spacer out from the inside.
It looks like the rubber O ring was pretty tore up, most likely because of the tight fit I have to twist it to get to the top screws for cables before I can remove it.
Anyway, Iput black silicone sealant on the manifold, slid the white spacer on, filled it it's gap and coated it as well, then slid the carb on.
When I snugged it up I got a nice even bead squeeze out around intake and secured it.
It took off like a banshee, no bog at all.
I just can't believe the air seal is so poor on these things!
Anyway, I still need to mess with gear ratios but no sense in it until Monday, I have more parts coming from Sick Bikes...
Expansion Chamber - BLACK - Exhaust Pipe $67.95
Air Filter - Low Profile $13.95
Plug Wire - High Performance $6.49
NGK BPR6HIX - Spark Plug - Iridium $6.49
Sub-Total: $94.88
Zone Rates (Shipping to US : 15.95 lb(s)): $16.00
Total: $110.88
The whole motor kit only cost me $10 more than that!
With any luck, those upgrades will power the new aggressive shift table I programed. If so it's going to be a spooky fast ride ;-}
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.
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.
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.
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.
YouTube - I Love Lucy - The Candy Wrapping Job
Lucy and the Chocolate Factory
re: shipped with parts missing.
Lucy and the Chocolate Factory
re: shipped with parts missing.
Has anyone received a Grubee CNS Carb with the top plate gasket? Mine came with out but I was none the wiser until I saw the rebuild kit. I'm going seal mine up and hope for the best. I would be a waste if we cant get suck a nice carb to work.
Oh and has anyone tried out the billet intake for the CNS form Manic Mechanic?
i just had a simple question about the choke lever on the new CNS carb. When is the choke activated when the lever is up and the wire is pulled out of the carb? So that would mean for a cold start push lever up (pull cable out of carb) and then push lever down once engine is running?
Thanks for the help.
Thanks for the help.
Cable pulled = "choke" on.i just had a simple question about the choke lever on the new CNS carb. When is the choke activated when the lever is up and the wire is pulled out of the carb? So that would mean for a cold start push lever up (pull cable out of carb) and then push lever down once engine is running?
Thanks for the help.
Cable relaxed = "choke" off.
It is actually an enrichment circuit. When you open it, it adds more fuel to the intake charge. It is a 3rd fuel circuit only used for starting and warm up.
O.K, So what about NT carb choke up or down for cold start? Just polishings Z2-80 ports on new motor, came w NT.
My skyhawk 49cc came w a CNS I've had no prob. maybe cause the intake is pressed againsed the seat tube.
My skyhawk 49cc came w a CNS I've had no prob. maybe cause the intake is pressed againsed the seat tube.
Can rtv clear be used instead of black? Or is it a 'gas thang' and I didn't understand?
Also, good to know that white plastic ring is supposed to be one piece. Mine is in three. I'll have to contact gasbike about that.
Bike has been sitting since I bought it in Oct-Nov, though I was out of state from J-18 to Feb 1st) and it won't start yet.
Also, good to know that white plastic ring is supposed to be one piece. Mine is in three. I'll have to contact gasbike about that.
Bike has been sitting since I bought it in Oct-Nov, though I was out of state from J-18 to Feb 1st) and it won't start yet.
I've been having similar problems with the CNS carb that came with my Skyhawk and i tried everything including sealing the gaps with a gas resistant sealant like this thread states. My engine still bogs under power and whats even worse is now when i pull the clutch in to idle its runs WIDE open sounds like the things about to explode and ive tried everything wound the idle screws all the way in, all the way out and everything in between, dropped the needle to the first notch and even tried it all the way up at the 5th, and made sure the throttle and choke slides are aligned and working properly and no change in the idle whatsoever it just always screams like its gonna kill itself wtf is wrong with this crap carb.
And on a side note a ton of gas splashes out from under my gas cap whats up with that. I've tried it in several different positions and my legs still get covered in gas.
This is my first build motorbike build but im no stranger to small engines and motorcycles. I knew going into that it would need some tinkering to get running right but im getting very discouraged because its literally one stupid head smashing ordeal after another. Its a shame cuz i hear so many optimistic things on this site but i have very few good things to say about my build so far.
My junk VW has fewer issues than this thing and that is saying something
And on a side note a ton of gas splashes out from under my gas cap whats up with that. I've tried it in several different positions and my legs still get covered in gas.
This is my first build motorbike build but im no stranger to small engines and motorcycles. I knew going into that it would need some tinkering to get running right but im getting very discouraged because its literally one stupid head smashing ordeal after another. Its a shame cuz i hear so many optimistic things on this site but i have very few good things to say about my build so far.
My junk VW has fewer issues than this thing and that is saying something
Let's start there.
Pull off the air cleaner and look inside the carb.
There should only be a sliver between the bottom of the sliding barrel and the bottom of the carb with no throttle. If it's a bigger gap it could be your throttle cable, the idle set screw, or the barrel is simply in turned 180 wrong.
When you can look in and work the throttle and the barrel goes up and down nice you are set.
Next check your choke cable and slide.
It's little brass barrel needs to go all the way for no choke. If it is getting hung up it is dumping in fuel in.
Once you can get it to idle set the idle gas/air mix.
Twist it's adjuster in until it starts to die, then out a 1/4 turn or so.
The plastic ring insert is 1 piece with a single grove.
You can still use it, just seal the opening around the carb at the intake pipe.
Or, get a Pirate Cycles CNS intake for $20.
It's in the Manic Mechanic section.
You don't need the plastic ring or any sealant or anything so I'm told.
I'll let you know, I have 2 on the way.
These carbs can and do work well when you get it on good enough, it's just a royal pain.
I do love the choke on the handlebars and the separate idle circuit has it's advantages.
ABOUT THE CNS JET
My problem now is I need to get more fuel in the mix.
I'm running as rich as she'll go, needle all the way up (clip on lowest setting).
I have a very light tan on the plug so it's not to lean to burn up, but when I get wound out under load I can tell she's starving for fuel, and I don't even have the larger perfectly ported intake on it yet.
So next is a larger Jet.
These carbs seem to be a Makuni knock off.
The CNS jet looks like this.
It has no markings on it all, so no size indication.
This should be replacements for them.
Note they are marked and range from 50 to 180 in 5's in size.
Any clue whatsoever what the CNS carbs we get is numbered?
I found this site while hunting for some kind of jet reference chart. Perhaps it can help you determine the size of the jet that the carb comes with from the factory as well as perhaps fine tuning, custom sizing a jet if you need to.
Affordable Go Karts - How to drill the main jets
Affordable Go Karts - How to drill the main jets
Outstanding find GearNut!
"The first thing we do is match the stock main jet to its corresponding numbered drill bit. If your stock main jet is a 100 (stock size in a 22mm Mikuni) you will find this jet size falls between the #62 & #60 drill bit. "
Good 'ole Harbor Freight is mentioned as a cheap place to get the bit set, and I have a dandy little 1/4" drill press for small bits.
I'll post back here what the jet size is, and what works for me with a good air cleaner, Pirate Bikes CNS Carb billet and SickBikeParts Xchamber.
Great thread..... after I go through all these posts I am going to adjust mine....
I have 2 grubee gt2b kits 48cc w/ the cns carbs.....
From the factory , they are not set correctly at all.
The first bike I built I though I did something wrong ..... the second did the same.
Both bikes will start / idle fine, but they completely die out on hills , even the slightest... I was told from a few people that it was the float ... ???
Haven't had time to mess w/ them ,,,, but as it gets warmer here i need to.
On flat ground and warmed up they do fine....
Overall though, not happy w/ the grubee kits.... i think if I bought the boygofast cheapy I would have been better off in the wallet and still had the same probs ...
I have 2 grubee gt2b kits 48cc w/ the cns carbs.....
From the factory , they are not set correctly at all.
The first bike I built I though I did something wrong ..... the second did the same.
Both bikes will start / idle fine, but they completely die out on hills , even the slightest... I was told from a few people that it was the float ... ???
Haven't had time to mess w/ them ,,,, but as it gets warmer here i need to.
On flat ground and warmed up they do fine....
Overall though, not happy w/ the grubee kits.... i think if I bought the boygofast cheapy I would have been better off in the wallet and still had the same probs ...
Is your carb level?
If so, and going uphill stalls you out then the float could be too low.
But you can run wide open right? No Bog?
If not, then it is most likely an air leak.
Pirate Cycles has a spiffy intake for the CNS carbs.
$20, but it solves the air leak problem and it's ported perfectly to the head.
The only problem is it is a short straight pipe, so if your motor leans forward you'll need to lower the float level to keep from flooding, but it's great going up hill ;-}
CruisinOCMD:
My man. You said what I've been thinking all day, messing with my new Skyhawk 48cc with the CNS carb - stands for central nervous system. Exact same problems with the bogging and revving, and I've been racking my brain for two days, and it crossed my mind to throw bike and motor in the yard for all to see and piss on it and train the dog to piss on it every time until the whole mess rots and goes away.
Brother, I cut my teeth on antique VWs, literally taught myself, and there's nothing on one I'd need another mechanic to fix but a transmission or a tortion bar. I once spent three hours trying to thread on the fourth engine mount nut - the one everybody leaves off - and never even got pissed, but I'm pissed today. I've seen every funky curve a funky system can throw at you, and I agree, none of them ever had issues like this here. One old guy looked at the thing and said, "prison-built."
I've taken all the adjustments away from factory settings to the ends of their ranges and back again. I redid all the wiring proper and professional and shrink-wrapped it. I tore down the carb, lubed and aligned the cables and links, torqued the head, and on and on. Came here because I was out of ideas, but guess what? Now I have a slew of new things to try because so many folks have been here before me. CNS indeed.
Never say die. This thing will work if I have to clamp it with my bare feet and weld it with an extension cord. Thanks for all the good tips guys.
My man. You said what I've been thinking all day, messing with my new Skyhawk 48cc with the CNS carb - stands for central nervous system. Exact same problems with the bogging and revving, and I've been racking my brain for two days, and it crossed my mind to throw bike and motor in the yard for all to see and piss on it and train the dog to piss on it every time until the whole mess rots and goes away.
Brother, I cut my teeth on antique VWs, literally taught myself, and there's nothing on one I'd need another mechanic to fix but a transmission or a tortion bar. I once spent three hours trying to thread on the fourth engine mount nut - the one everybody leaves off - and never even got pissed, but I'm pissed today. I've seen every funky curve a funky system can throw at you, and I agree, none of them ever had issues like this here. One old guy looked at the thing and said, "prison-built."
I've taken all the adjustments away from factory settings to the ends of their ranges and back again. I redid all the wiring proper and professional and shrink-wrapped it. I tore down the carb, lubed and aligned the cables and links, torqued the head, and on and on. Came here because I was out of ideas, but guess what? Now I have a slew of new things to try because so many folks have been here before me. CNS indeed.
Never say die. This thing will work if I have to clamp it with my bare feet and weld it with an extension cord. Thanks for all the good tips guys.
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