CNS V2 versus Speed carb

K

kojak

New Member
My bike was delivered with a CNS V2 carb installed, and even though I felt it was working properly I decided to try out the Speed carb based on opinions here that it was superior.

I used the Speed carb for about twenty miles over three days and found my cruising speed (top speed before the motor sounds strained) had increased from 35 to 38; unfortunately acceleration was noticeably weaker and the bike was less fun to ride. It was also unusually difficult to start--a problem that I had solved in the past when I switched to NGK plugs.

Meanwhile I dismantled the unpopular CNS V2 and found that the main jet had almost completely unscrewed itself. I reassembled it using parts from the CNS rebuild kit, including a pointless new gasket for the top cover and the metal floats.

I've reinstalled the CNS, and the punchy acceleration came back. It also went back to starting quickly which is extremely important to me since my bike is difficult to peddle. Idle and air/fuel screws needed to be much further in than they did before with the loose main jet. I'll do some speed testing soon.
 
Uh oh--my shakedown run didn't go so well. Bike ran strong for three miles then suddenly lost power and wanted to stall. I limped home at maybe 15MPH with the throttle wide open. Pulled the spark plug and it was mostly black and oily, with a little grey at the very tip.

Any ideas? Maybe my main jet came loose again and fell off completely this time?
 
Thanks?

Anyways, turns out my guess was right and the jet was sitting on the bottom of the bowl. I used a tiny dab of Loctite this time.
 
It feels better than ever, but I can't really do any more direct comparisons since I also added an expansion chamber.

In all honesty, I can't find anything "wrong" with the CNS V2 (C-32CNS66-EPA) once I had it put together properly and solved the air leaks. It's internally well made and my bike seems to respond well to the larger bore compared to the Speed carb.
 
I had the same issue. I ordered a speed carb and the jet was sitting in the bottom of the bowl. There were no threads in the jet tube! I tapped new threads and all is well.
 
No problems with a Speed carb on a billet intake- lots of pep.
No experience with any CNS

have had some weird problems with 49cc with "sleeved" NT carb- I think the float is sticking- had it apart once- would like to put the old billet and old NT carb on that was running good, but the long sleeve studs are spaced differently, so it'd be a little bit of a mod- it runs pretty good when it does though- because there's no intake at all! thecarb sits righton the motor-

I think the length counts- closer to the motor the better- never liked the idea of alonger offset intake myself
 
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