OMG I have to tune a CNS!!! Help

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biknut

Well-Known Member
Sep 28, 2010
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I'll try that. I put an o-ring in there and it seems to work, but maybe it's leaking there. Couldn't hurt I guess. Also what I was wondering is if anyone tried sealer where the upper and lower halves of the carb come together. Is there a gasket in there already?
The float bowl does have a gasket. I doubt you would need to use any sealer there.
 

droc089

New Member
Jun 25, 2011
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ohio
Would it be a good idea to run the C-clip on the lean side more like second from top, or the top since mine runs pretty rich, how bad will that kill the power side of things?
 

biknut

Well-Known Member
Sep 28, 2010
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Would it be a good idea to run the C-clip on the lean side more like second from top, or the top since mine runs pretty rich, how bad will that kill the power side of things?
It won't hurt anything to try leaning out the needle. If it runs worse you can always change it back.

I had to run mine in the richest position on the 80 I tuned. It didn't like any other position.
 

biknut

Well-Known Member
Sep 28, 2010
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Everyone's bike is different - I run second from leanest.
Yeah that's true. One problem I've noticed on the forum is someone says my bike runs like crap what do I do? But most of the time they forget to mention what brand, size, modifications they may have. It makes a big difference.
 

rustycase

Gutter Rider
May 26, 2011
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Left coast
+1 what Biknut said about plugs...
Way back when I really wanted to run Champion plugs on my dirtbikes, I learned NGK was far superior.

...seems to me that the outer ring of the plug, (the threaded part?), being tan in color, and the center electrode being black, kinda wet, is kinda backwards what you might want to see. It's kind of odd... It would lead one to believe you have too cold a plug, but the cylinder head itself is running hot.
Although, with E-85 fuel, I have been told ALL plugs in an engine should be more to the black side than tan because of how the alcohol burns???
I am not an expert on reading plugs.
Good luck
rc
 

biknut

Well-Known Member
Sep 28, 2010
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I'm glad I can finally join in this topic.


I am the proud owner of a CNSv2/GenB carb, and I'm even prouder that I got it working.

Everything I did is as follows.

Tightened BOTH jets.
Adjusted float tang.
Chopped choke cable.
Replaced cover with drilled out NT cover.
Replaced intake with MM intake (though I should have tested teflon tape first).
What's the altitude where you live? I'm at about 680'
 

skrew37

New Member
Feb 23, 2011
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Pennsylvania
I checked my plug today before work and it's finally a nice chocolate brown! Last night I took my carb apart and tightened everything down as it all seemed just slightly loose. One kind of scary concern is a while back I put two o-rings in to seal the intake. One fit the i.d. of the intake manifold and another fit the i.d. of the larger o-ring which was the same size as the face of the intake, if that makes sense. ANYWAY, when I removed my carb from the intake and looked inside, I only found ONE o-ring. Could my motor have consumed the smaller o-ring? I can't find it. I haven't had a chance to remove the intake yet, as I'm hoping it's just lodged down in there and hadn't made it in to the engine yet. Either way, it's running better. And I have another little project tonight.
 

biknut

Well-Known Member
Sep 28, 2010
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Is it best that i break my engine in before i drill the main jet?
Kind of depends how it's running. Mine ran so bad it would barely do 10 mph, but it would start and idle ok. I had to tune it a little just so I could ride it. Just don't try to get it perfect till after you get off the break in mix.
 
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Greg58

Well-Known Member
May 1, 2011
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Newnan,Georgia
Biknut is right, get your bike to run then after the break in you will most likely have it tune the carb. It took about 250 to 300 miles till mine felt stronger, so if you can ride it the way you have it now be it rich or whatever you may be o/k.
Hey droc if you are too rich you may lean it out some with a SBP air filter, I had to drill my main jet to a 68 on a 48cc. before i drilled it I put the stock filter back on and it ran normal. I just like the better filter.
 
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skrew37

New Member
Feb 23, 2011
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Pennsylvania
I put the carb back on and tightened everything down. All seemed great until I opened the fuel valve to let in some gas. It overflowed the carb and started leaking (pouring) out of every hose and out of the air filter. What's happening?
 

biknut

Well-Known Member
Sep 28, 2010
6,653
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Dallas
I put the carb back on and tightened everything down. All seemed great until I opened the fuel valve to let in some gas. It overflowed the carb and started leaking (pouring) out of every hose and out of the air filter. What's happening?
For some reason your float needle isn't closing. Check that first. It'll be easier if you take the carb off the bike.

Make sure the pointy end of the float needle is going into it's seat.
Clean the float bowl out.
 

droc089

New Member
Jun 25, 2011
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ohio
I put the carb back on and tightened everything down. All seemed great until I opened the fuel valve to let in some gas. It overflowed the carb and started leaking (pouring) out of every hose and out of the air filter. What's happening?
I had this same problem. I believe it's your float needle or float. After mine overflowed and spilled gas on everything, I opened the float bowl and the float needle fell out. I put it back and and everything worked fine.