CNS Carburetor

[BarelyAWake]

Right on stv1jzgte

 

[john_the_great]

I definitely didn't just slap this carburetor on, i gave it every chance I dunno how the guys that are claiming success out of it got it to be a better carb then stock. I got it to run usably but then it started leakin' and I got flashbacks of all my old motorcycles with with leaky carbs... (ps: tune your carb when your bike is completely warmed up)

 

[john_the_great]

There are no tubes on the carb for oil injection. The way the Yamaha engines that use the Mikunis that these are a knockoff of work is there's an oil pump driven by a gear on the crankshaft, and the oil drips directly into the bottom of the cylinder.

One of the tubes on the carb is a vent tube down into the bowl, which should be left open. That vent tube allows air to enter the bowl when the fuel level in the bowl drops. Close that vent, and you don't get good fuel flow. There's another tube that should be capped, though. On the Yamahas, that runs vacuum to a diaphragm-style petcock. So you never need to manually open the petcock; the vacuum diaphragm does it all.

There's a teeny tiny pilot jet in these that gets gummed up easily without 2-cycle fuel mix. I have to think that running 40:1 through this carb's passages is going to plug that pilot jet in no time, which would give you crappy idle.

I've mentioned this before, but it's worth mentioning again. This carb most certainly takes Mikuni jets - main and pilot - if you want to replace what's there.

I'd say given the fact that this carb isn't a mikuni, and the fact that yamaha used their vacuum petcocks on modern 4-stroke bikes. Not 80cc 2-stroke scooters from nineties, and the fact that the Yamaha cy-80 was oil injection... (by the way ive tried mikuni jets they don't fit, THIS ISN"T A MIKUNI CLONE! it is its own carb)

 

[Venice Motor Bikes]

I love this thread, "crap carb" no "its a great carb" "doesnt work properly" "works great"
"Fuels leaking"

If you cannot tune it propery it must be defective....right?

I wont boast mines the fastest mb with the CNS but it works great for me.

The biggest problem i have seen with this carb is alot of people have jumped from the nt to the cns, dellorto or what eva carb without any understanding of how the first 1 worked in the first place, oh its not working for me so im gettin the other 1, like the guy who tuned his cns carb by just idleing, yeh that sound about right sweeet.
You cannot just screw the idle screw in 2 1/2 turnes jet this big and needle on the second notch, she dont roll like that there are numerous things to consider elevation, temp, fuel octain, oil ratio, size of your airfilter etc etc.
Anyone contemplating a different carb should first ask themselves do i really know how this 1 works and will i know how a slightly more complicated 1 will work?

What you just said has already been said a half dozen times in one form or another.

 

[stuartracing]

I have pleny of power with the stock carb....I have my bike haulin ass.....Idles sweet,a little on the rich side,I do have a Boost system on mine and running a Lawn mower muffler....Goes as fast as 35 to 40 mph, thats as faast as I need to go on a bike,lol....

 

[stv1jzgte]

What you just said has already been said a half dozen times in one form or another.

Yes but its right aye! kinda like alot of points/opinions and facts in forums they get flogged to death.

I bet the other 5 people who said it to all there's work fine.

Anyway im happy i have 1 of the only working cns carbs around, i guess its unique now.

 

[Venice Motor Bikes]

Yes but its right aye! kinda like alot of points/opinions and facts in forums they get flogged to death.

I bet the other 5 people who said it to all there's work fine.

Anyway im happy i have 1 of the only working cns carbs around, i guess its unique now.

Actually, I've said that before too, on other threads.
I'm pretty good @ carb tuning & I think the problem with the one I was working on was with the engine not the carb.

 

[sportscarpat]

Actually, I've said that before too, on other threads.
I'm pretty good @ carb tuning & I think the problem with the one I was working on was with the engine not the carb.

I would agree it was the engine. I have two CNS carbs. They are both bone stock, nothing modified and they work great. I did all the tuning adjustments on the first one. Tuned it till it ran perfect and the adjustments ended up being right back were they were when I received it. On the second one I threw it on, adjusted the idle and haven't touched it again. What I have found is that my bikes run smoother with the CNS and don't four stroke. I attribute this to a better quality needle. The smoother the fuel/air mixture enters the engine the smoother the engine runs. For all those unloved CNS carbs out there, just send them to me and I will give them the love they deserve. Enjoy your NT carbs, I'll stick with the CNS.

 

[john_the_great]

sooo.... it revs out past 4000rpm for ya?

 

[sportscarpat]

sooo.... it revs out past 4000rpm for ya?

I don't have an RPM gauge, but my nice heavy 1954 Schwinn Panther with a PK-80 hit 38.5 mph the other day and can cruise comfortably at 30 mph. My boardie can hit 36 mph and also cruises at 30. Both run nice and smooth. Speeds were verified on my $10 Schwinn digital speedo. Maybe there are some quality issues with some of these carbs. Your here in California, send me the carb and I will try it for myself and see if I can get to the bottom of it.

 

[stuartracing]

When I had the CNS carb, on my bike I ran a line from the float bowl over flow vent nipple(bottom of bowl) to the open vac nipple on the carb. so when I was blasting full throttle it pulled fuel from the bowl vent and gave me a secondary jet system so to speak.....

 

[john_the_great]

My other question is which intake manifold did you use, what displacement engine(and what company its from), what your gearing is, what pipe you used, and what fuel/oil mixture.

 

[stuartracing]

When I had mine you had to creep up on the rpm`s...You couldn`t just whack the throttle open, you had to feed it a little bit at a time...It was really sensitive off idle.....

 

[palmclub]

Mornin guys ,, hey does anyone stock parts for these carbs my kid was tunein his up last nite and the air adjustment spring and screw rattled lose and bounced down the road ,, were lookin for it but if someone has spare parts that would be very cool thanks Poul

 

[stv1jzgte]

When I had mine you had to creep up on the rpm`s...You couldn`t just whack the throttle open, you had to feed it a little bit at a time...It was really sensitive off idle.....

Ive busted 3 black plastic throttle assy's i cannot whack it open fast enough!

 

[stuartracing]

Aaah, I hear ya on that....

 

[BarelyAWake]

NAPA has an all metal one fer like $10-15... no kill switch tho *shrug*

part # 7-03921

 

[stuartracing]

NAPA has an all metal one fer like $10-15... no kill switch tho *shrug*

part # 7-03921

No way....Cool,I have a NAPA right up the street...I wonder what they sell throttles for at NAPA....
I`ll have to check one out....
Thanks.....
Paul....

 

[BarelyAWake]

They've got some random pitbike/gokart kinda stuff, it's prolly all catalog items... we've got the "big book" where I work heh

That throttle is still made in china/taiwan w/e & the grips suk, but it's solid that's for sure and the twist tube is metal too - it's a lot better than the kit ones.

 

[tweeked]

I got my carb today and it doesnt fit the intake(factory or stock)?