OMG I have to tune a CNS!!! Help

droc089 said:
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?
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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.
 
DuctTapedGoat said:
Everyone's bike is different - I run second from leanest.
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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.
 
+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
 
DuctTapedGoat said:
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).
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What's the altitude where you live? I'm at about 680'
 
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.
 
jtgolden said:
Is it best that i break my engine in before i drill the main jet?
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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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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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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?
 
skrew37 said:
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?
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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.
 
skrew37 said:
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?
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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.
 
You mean the needle on the slide? there's another needle? That sucks I spent an hour trying to get things perfect. I'll have to check it tomorrow. Thanks guys.
 
skrew37 said:
You mean the needle on the slide? there's another needle? That sucks I spent an hour trying to get things perfect. I'll have to check it tomorrow. Thanks guys.
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No, not the needle slide.

There's another needle in the float bowl that stops the gas coming in when it's full. Don't worry, it's easy to fix. Yours probably just fell out like droc's.
 
The float needle is spring loaded to cushion the mechanism against shock and bending when you ride over bumps and ruts as the fuel sloshes around inside the float bowl.
It is common in every major brand motorcycle carburetor made after 1980ish.

Set the float height with all free play removed from all touching parts, spring loaded plunger not yet compressed into the needle.
 
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