a tale of 2 carbs

rickie h · Dec 31, 2009

so guys im deff buying a bigger carb my 66cc has a 48cc carb...so im narrowing it to these 2...in your professional opinion which of these 2 carbs will give me the best overall boost based on power,speed,engine health,and fuel economy(im aware im gonna use more fuel with a bigger carb)
im mainly looking for more speed and something to get me up steeper hills
im willing to guess the more expensive one will do better but it cant hurt to ask
if youve used one of these 2 before please tell me about it
im not looking for deltoro or w/e carbs but other suggestions will be appreciated
just for added info im usually at high rpms
thanks

heres my carb choices

New Style 66cc NT Carburetor

CNS Carburetor for Motorized Bicycles

stv1jzgte · Dec 31, 2009

Well the "new style NT is no different to the old 1 other than the extra fuel shut off.

I have a cns on a 48cc its awesome.

rickie h · Dec 31, 2009

well it says and i quote "For the SkyHawk line of bicycle engine, the NT factory produces a carburetor designed solely for the 66cc engine. This newly revised carburetor incorporates a larger barrel slide throttle body for increased performance and a secondary shut-off valve on the carb itself to avoid accidental overflows. This new carburetor has the air intake & discharge hole diameters 3mm larger on both sides of brass slide. The main jet is slightly larger for improved performance, there is a better screw connection at the gas inlet tube, and the new fuel shut off valve remedies the older problem of leaking carburetors. Up until now, all NT carburetors were solely designed for 48cc engines."

stv1jzgte · Dec 31, 2009

rickie h said:
well it says and i quote "For the SkyHawk line of bicycle engine, the NT factory produces a carburetor designed solely for the 66cc engine. This newly revised carburetor incorporates a larger barrel slide throttle body for increased performance and a secondary shut-off valve on the carb itself to avoid accidental overflows. This new carburetor has the air intake & discharge hole diameters 3mm larger on both sides of brass slide. The main jet is slightly larger for improved performance, there is a better screw connection at the gas inlet tube, and the new fuel shut off valve remedies the older problem of leaking carburetors. Up until now, all NT carburetors were solely designed for 48cc engines."

Yeh i read that to, i also read here that there is no difference internally to the old 1, but if your sold on that go for the new nt.

But i will say this, the air/fuel screw on the cns is worth 50bucks alone

rickie h · Dec 31, 2009

i bet it is, i need one that i can tune to run at high rpms,what i am really sold on is a handlebar mounted choke tho,does it come handy a lot?and is it responsive?how is that set up?

BarelyAWake · Dec 31, 2009

The new NT is marginally different internally - the needle is slightly shorter with a bit more of a taper, the jet is a touch larger and the slide itself is also a hair bigger - enough so the slides don't cross over between carbs.

All this I noticed when I tried to rebuild my old carb w the guts outa the new one...

Having said all that - there still isn't enough of a difference to consider it a "performance" carb, it's just a lil better for the 66cc than the one it used to come with lol I would definitely try the CNS! Yet for the price it is bordering on getting a real carb - like the Dellorto I'm considering: PHBG 16mm AS Carb (Clamp On Style) 2 Cycle [D0-2511] - $84.20 : Dellorto Carburetors, And parts for you.

*shrug* It's up to you lol, I've still not made up my mind

Zenoptic · Dec 31, 2009

I am thinking of using the Dellorto SHB 16 off of my Vespa Primavera and just upgrade the Vespa with a SHBC 19/19. Both get an upgrade that way. May have to down jet the SHB fof the PK80. Just my thought on carbs.

Riding Rich · Dec 31, 2009

Im personally sold on the DELLORTO PHBG and convinced it will be the best carb to use.
Why why why??????????????????????????

Tuneability.

There are several stages of progression throughout the carburation.

The Stock carbs and othe Performance carbs lack real tuneability.

The PHBG is totally tunable.
The others you tune for 1 rpm but sacrifice power at other rpms.

Read up on tuning a DELLORTO like on MOPEDARMY.
Google IT.
Then you will understand.

Heres how it goes basically.

DELLORTO PHGB

Tuneable Starting Circut ( YES )
Tuneable Idle Circut ( YES )
Tuneable 0 to 1/8 throttle for low rpm ( YES )
Tuneable 1/8 to 3/4 throttle for mid rpm ( YES )
Tuneable 3/4 to WOT ( YES )

Show me any of the normal HT carbs that can do that.
I'ts not the size theese engines only need 15 to 16 mm carbs anything more is too much and not good.

If you can tune the carb to run perfectly in ever rpm range you will get the most out of the motor.

If your gonna port and mod the engine this will be very important.

Also the DELLORTO has available Needles, Jets, Slides, for every circut in the carb.

Spend the extra $20.00 or just keep the stock carb.

A bigger carb dosent mean more power a properly tuned carb = MAX POWER.

stv1jzgte · Dec 31, 2009

Riding Rich said:
Im personally sold on the DELLORTO PHBG and convinced it will be the best carb to use.
Why why why??????????????????????????

Tuneability.

There are several stages of progression throughout the carburation.

The Stock carbs and othe Performance carbs lack real tuneability.

The PHBG is totally tunable.
The others you tune for 1 rpm but sacrifice power at other rpms.

Read up on tuning a DELLORTO like on MOPEDARMY.
Google IT.
Then you will understand.

Heres how it goes basically.

DELLORTO PHGB

Tuneable Starting Circut ( YES )
Tuneable Idle Circut ( YES )
Tuneable 0 to 1/8 throttle for low rpm ( YES )
Tuneable 1/8 to 3/4 throttle for mid rpm ( YES )
Tuneable 3/4 to WOT ( YES )

Show me any of the normal HT carbs that can do that.
I'ts not the size theese engines only need 15 to 16 mm carbs anything more is too much and not good.

If you can tune the carb to run perfectly in ever rpm range you will get the most out of the motor.

If your gonna port and mod the engine this will be very important.

Also the DELLORTO has available Needles, Jets, Slides, for every circut in the carb.

Spend the extra $20.00 or just keep the stock carb.

A bigger carb dosent mean more power a properly tuned carb = MAX POWER.

Yep i couldnt agree more but that thing cost more than a new motor! $84+ and the CNS carb at $50 is 10 times better than the new NT for $30

stv1jzgte · Dec 31, 2009

rickie h said:
i bet it is, i need one that i can tune to run at high rpms,what i am really sold on is a handlebar mounted choke tho,does it come handy a lot?and is it responsive?how is that set up?

Yeh my poor motor see's some constant high rpm's and i cannot get the NT to perform like the CNS, more torque down low and top end is a few kmh faster and responsive, but as riding rich clearly said aint as tuneable as the dellorto but its miles ahead of the NT new or old style.

The choke is cool, though i live in Oz and its hot here all the time so i dont need it for startup. I dont run a kill switch so i use it to turn the motor off.
Good luck with YOUR choice!

Riding Rich · Dec 31, 2009

I only use the choke for starting.
And for shutting off the engine.

If you need the choke during normal operation
your jetting is not correct or you have an air leak.

Alot of things influence how these motors run and if you don't have an Expansion chamber I'd spend my money on that 1st.

I go from 0 mph to 40 mph pretty quickly and my engine runs smoothe at high rpm.
I'm using the carb that came with my stock grubee 48 on a PK80. "36T"

stv1jzgte · Dec 31, 2009

Riding Rich said:
I only use the choke for starting.
And for shutting off the engine.

If you need the choke during normal operation
your jetting is not correct or you have an air leak.

Alot of things influence how these motors run and if you don't have an Expansion chamber I'd spend my money on that 1st.

I go from 0 mph to 40 mph pretty quickly and my engine runs smoothe at high rpm.
I'm using the carb that came with my stock grubee 48 on a PK80. "36T"[/QUOTE

if you get an epansion chamber and a carb you should hit 50 eh

Outrunner · Dec 31, 2009

Riding Rich said:
I only use the choke for starting.
And for shutting off the engine.

If you need the choke during normal operation
your jetting is not correct or you have an air leak.

Alot of things influence how these motors run and if you don't have an Expansion chamber I'd spend my money on that 1st.

I go from 0 mph to 40 mph pretty quickly and my engine runs smoothe at high rpm.
I'm using the carb that came with my stock grubee 48 on a PK80. "36T"

I agree with Riding Rich, which is to first buy an expansion chamber to help your
engine "breathe". Then try a better and larger carb. I mounted a Mikuni 18mm carb #VM18-144 on my 66/80cc engine and it FLYS!! I have a digital tachometer that reads very accurately by counting the spark impulses from the spark plug wire, and I easily run well over 7000 rpm with it. Here's a picture of it with the manifold that I modified.

Zenoptic · Dec 31, 2009

Riding Rich said:
Im personally sold on the DELLORTO PHBG and convinced it will be the best carb to use.

A bigger carb dosent mean more power a properly tuned carb = MAX POWER.

Are you talking about the powder coated black raceing version with the plug in the flot bowl for easy access to the main jets? Fantastic carb!

rickie h · Jan 1, 2010

you mean the fat exhausts?wheres the cheapest place to get one?are they honestly that good?and since its fatter can you still pedal?
thanks for the tips!

BarelyAWake · Jan 1, 2010

An expansion chamber is an integral part of a two stroke engine, reflecting part of the shock wave from ignition - it has a similar effect as the exhaust valves on a 4 stroke. While you can run without this "performance" upgrade, I consider it an essential component only left out due to their really low price of the kits.

Prices vary as does the responsiveness - a pipe really outa be tuned to a specific engine type but you can get "pocket bike" expansion chambers really cheap. Spooky Tooth has a nice one that's a simple bolt on - I've got the Sick Bike Parts system and I'm very pleased with it and its the only one that's tuneable to both your engine and the fit of your bike.

They really do "wake up" yer motor

Riding Rich · Jan 1, 2010

I also have an SBP pipe and i have slightly ported my engine. " Changed The Timing"
You will need to tune the pipe to fit your riding needs.
The length of the pipe coming from the port is adjusted to time the return of the sound wave. The sound wave actually closes the exhaust port before the piston closes it.
Ramming the fuel charge that escapes out of the exhaust back into the cylinder and increases the pressure in the cylinder on the compression stroke.

captainrichhill · Jan 1, 2010

I bought one of those "new NT carbs" and I didn't see any noticable difference in ANY catagory from the stock carb with proper size jets.
Try the CNS or Mikuni. Being able to adjust the fuel/air mixture is worth it to get your motor to run like it can and should.
My $.02

motorhead419 · Jan 5, 2010

rickie h said:
well it says and i quote "For the SkyHawk line of bicycle engine, the NT factory produces a carburetor designed solely for the 66cc engine. This newly revised carburetor incorporates a larger barrel slide throttle body for increased performance and a secondary shut-off valve on the carb itself to avoid accidental overflows. This new carburetor has the air intake & discharge hole diameters 3mm larger on both sides of brass slide. The main jet is slightly larger for improved performance, there is a better screw connection at the gas inlet tube, and the new fuel shut off valve remedies the older problem of leaking carburetors. Up until now, all NT carburetors were solely designed for 48cc engines."

The new carb is 1 mm bigger, not 3 mm. I had one before I got a 18 mm Mikuni with a straight intake.Newest pipe picture by alan321 - Photobucket

Riding Rich · Jan 6, 2010

Ive seen some reed block setups that come to hook up with the PHBG.
Gonna buy 1 and make a maniflod for my intake.

a tale of 2 carbs

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