CNS carb

GoldenMotor.com
Creative Engineering

Creative Engineering

New Member
Sep 20, 2008
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I've seen a lot of complaints about this carb...

Who has fine tuned this carb?

I haven't had a chance to build a bike with the latest Grubee engine that uses the CNS carb. I have one here...but I haven't run it yet.

Anyone have any suggestions for the others? Or am I going to have to do it? It's not a bad carby...it's actually far better than the NT. Yes...I can say this without even having run it yet!

Jim
 
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oddfellow74

New Member
Oct 7, 2010
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west virginia
i have two of them and they are crap i have adjusted every way known to man and the only way they will run halfway decent is if i adjust the airscrew completely in and set the needle clip on 5th notch
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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Ya prolly know this, but the aftermarket upgrade CNS and the "CNS" included with the 2010 Grubee motors are two entirely different beasties - so there's more than just a little bit of confusion lol

When the aftermarket upgrade CNS first hit the market I picked one up & with just a lil fiddling it worked flawlessly, and has continued to for the almost 4500 miles I've had it. The only "problem" I've had was a lil bit o'grit or something in the float's shut off valve that cause it to overfill & dribble... easy fix ofc and not a problem limited to the CNS lol

I dunno much about the "CNS" included with the Grubees other than the pics & info ppl have offered here on the forum, but I will say one thing - "gluing" the fuel/air mix and idle set screws in place so ya can't adjust them for your environment is prolly the most pants-on-head dumb thing I've heard of in quite a while & completely defeats the point. Granted, that was most likely done to be compliant with today's regulations - small Yamaha outboards sometimes have those screws capped off so ya can't mess w/them for that reason alone... but that doesn't make it any less dumb as my buddy the Yami tech would be more than happy to tell ya... over and over and over again heh
 
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Hammond Egger

New Member
Oct 23, 2010
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Tucson, AZ
They aren't shipping this carb with all 2010 66cc motors, or at least they aren't now. I got one yesterday and it had the carb with the red air cleaner cover on it. The motor I got that had this carb was the CF clutch and pull start model.
 
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riff44raff

New Member
Nov 4, 2010
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staton ca
Assembly and operation manual try this !!! go down the page to the carb part . its not the same carb but close and the princable is the same ! when I got mine ( aftermarket ) I was told dont mess with the adjustments lol !!!! thats why I got it ! works great for me ! I did find that a bigger air filter helped alot I got a k & n 62-1390 62-1390 - K&N Crankcase Vent Filters, Vent Filter helped alot a bit pricy and I had to cut it down and re glue it with rtv red with that and the expantion chamber I got the needle all the way down and going to git a bigger main jet .I'll try a 0.74 first I think stock is 0.70 I hope that helps oh and the link says the 2 adjustments are for idle only well I've found mine runs better at wot with the mixture turned in just a bit it gives a little ruff idle but better at wot also when I got it the adjustment screws had something on them (clear could not see it )that held the screws in place sort of like some sort of locktite or nail polishand now I got it diled in I want to put something on the screws to keep them from moving but still able to move if I want . maybe green locktite ???? any sugestions ????
 
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riff44raff

New Member
Nov 4, 2010
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staton ca
oh ya also I took the needle out of the old nt carb and put the nt needle in the cns !!! the nt needle has a better taperd point and helped a little too and too think I got all this info hear at this place !!! thanks everyone ! also I got one of those short billit intakes from pirate and cut the intake gasket to match .you got to cut the cluch bolt down to make it fit but well worth it . now I got to get the dremel out and port & polish the head !
 
WildAlaskan

WildAlaskan

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Sep 30, 2010
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alaska
barely awake said:
Ya prolly know this, but the aftermarket upgrade CNS and the "CNS" included with the 2010 Grubee motors are two entirely different beasties - so there's more than just a little bit of confusion lol
Click to expand...
what!!! that cns carb was the primary reason i ordered that kit i had heard good things about the cns but man false advertisment that is angering
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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However - I'm not sayin' the stock "CNS" on the Grubee kits is a bad carby - I wouldn't know as I've not had one lol, I'm jus' pointing out that they're different, even the "glued" set screws I've only heard about & not seen, but I assume a lil heat & patience could prolly fix that right up.

In fact, the new Grubees are supposed to have larger intake & exhaust ports & if that's true - then it's defo worth it for that alone I figure, so I'd not be too disappointed WildAlaskan... heck, even if they're just cleaner castings than before it'd be awesome ;)
 
Pablo

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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Always good info here!! Good photos - people need to understand the "CNS" carb still needs a jet change for off idle air/fuel adjustment (particularly at WFO).

I have not fondled a stock long dong Grubee CNS so we will need to get one to check the jettage. We do have an aftermarket CNS. On Monday I will measure the stock jet size (optically - very accurate). These are 6mm main jets (NT's are 5mm), but the jet screw is slightly longer than the Del Orto equivalent, but looks like it will work.

That said - we are looking for volunteers to try out some jet sizes. We will make a separate thread for that next week or so. Ride on!!
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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*cough* might need a jet change or clip position change Pablo, tho that's a minor detail to be sure ;)

I did pretty much jus' slap my CNS on my engine n'went, while I fiddled w/it for a while - I never needed to alter the clip setting nor change jets... ofc I'm at (and sometimes under aargh) sea level, which would mean it might be kinda rich for others... still, I think for most it'd prolly be just a simple clip adjustment w/the aftermarket CNS anyway *shrug*
 
Pablo

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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Actually good to know!

People like to have their spark plugs just so. Others are looking for WFO performance with a pipe and such. Usually takes a jet size change to get there, but not always.
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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Maine
True, very true - jus' to clarify a lil more for the sake of precision & attempted diagnostics - I'm @ sea level runnin' 100:1 Amsoil 'Saber' synthetic in a 66cc Grubee, lightly ported, lapped head & with your expansion chamber & NGK BR4HS Iridium gapped at .030 :D


I also like curling up w/a good book while listening to... wait... wrong forum o_O :p
 
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sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
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california
Pablo said:
That said - we are looking for volunteers to try out some jet sizes. We will make a separate thread for that next week or so. Ride on!!
Click to expand...
I'm game for some testing and have three CNS equipped bikes sitting right here. They have #61 jets as I recall (need to double check) and are all too rich, although running well otherwise. I sent you an email.
Thanks
Pat
 
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Hammond Egger

New Member
Oct 23, 2010
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Tucson, AZ
Pablo said:
That said - we are looking for volunteers to try out some jet sizes. We will make a separate thread for that next week or so. Ride on!!
Click to expand...
Pick me, pick me! I have three CNS carbs. I know how to adjust the float, adjust the idle and air mix, change the jets, change the c-clip setting and I can factor polynomials.
 
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