what is the best carby to use?

[motorized kodiak]

hey everyone, which carburettor is the best to use, in terms of performance, does it even add any hp or power? and does a performance air filter make a difference to performance? which one of these should i get? thanks in advance!
http://www.sickbikeparts.com/catalo...ducts_id=40&osCsid=e60rk8kaodheccdoa9dg6shvc7

http://www.sickbikeparts.com/catalo...ducts_id=99&osCsid=e60rk8kaodheccdoa9dg6shvc7

 

[maniac57]

You're going to get a lot of people who disagree with me on this, but in my opinion, a stock china doll will not benefit much (if at all) from a carb swap.
I prefer the stock NT carb for simplicity and ease of adjustment.
The RT (speed) carb is very similar but slightly larger.
If I were to try a swap, it would be to a RT or speed carb.
The air filter will also make very little difference on a stock engine, but anything that improves air filtration is a good thing. Think CLEANER air rather than MORE air.

 

[dodge dude94]

^+1 to all that above. Additionally, either of the two filters you have listed are going to flow way more air and filter far better than the crappy filter/housings that these stock carbs come with.

Just something to think about.

 

[2door]

Ditto:
Just because it says, "high performance" doesn't mean, high performance.
The stock NT carb will provide you with about all the Chinese 2 stroke is capable of.
The placebo effect of bigger, aftermarket carburetors might be okay for some but the fact is the engine can only utilize so much air and fuel. Unless there is substantial modifications to the engine stick with what came with it. You, your wallet/credit card and your engine will be happier.

Tom

 

[FMB42]

There's an old track saying that says "torque wins races" that I fully subscribe to. And, in this respect, larger carbs aren't always the "answer" to better performance.

As for air filters, larger and more efficient (i.e. better air flow and, more importantly, more effective filtration) is always an improvement imo.

 

[rogergendron1]

the carb you select has to have a venturi opening the proper size for your motor, stock should be fine with a 14-15mm carb and yes a k&n stlye filter does help with air flow fuel economy and power though it may be so small its not noticable.

like i said stock motor loves the 15mm size carb if you go any bigger on a non ported stock motor your motor will not be able to draw air though the larger opening fast enough to meter fuel up through the jets... lager hole the slower the air moves through it the smaller the hole the faster the air moves through it, and faster is better !!! you want a carb with a venturi that is small enough that the air the motor is sucking moves quickly though it but not so small its restricting air flow at high rpms and it needs to be big enough so that at high rpms it can still flow easy but not so big that it cant move the air fast enough at idle to meter correctly

to big of a carb and low end to mid range suffers , you get top end but only so much can be had before any bigger is wasting space

to small of a carb aand top end suffers because the venturi is to small for enough air to flow through at high rpms.

the stock NT carb is a happy small carb that will give you just enough air to reach 7,000 rpms and have plently of low end power and easy tunability

the cns is a bit bigger and offers a higher top end wile still maintaining a venturi size small enough to meter fuel down low without problems, i would say the cns carb IS an upgrade from the stock NT carb if your looking for higher rpms and your real good at tunning a carb they are finiky.... hard to tune ...

just because the cns is bigger than the nt at the venturi and allows for higher rpms it does not mean your bike will be any more or less powerfull with it on there ! the nt carb with its smaller opening will have a better low end and begining midrange than the cns and pull right past it up until the high rpms then the cns will catch up and walk past it if all things were equil on bolth bikes.

the point is you need to choose a carb based on what type of riding your going to do...

high rpm race riding... you get in gear and keep the rpms up above 1/2 throttle for most of your riding you could benifit from a carb with a larger venturi opening to help flow more aiir in at those rpms. 16mm-18mm

you put around town at 25-30 and tackle hills, carry a lot of wieght and stay in the midrange,? go with a moderate carb like the cns mikuni clone or dellorto bolth 15.5mm

say you drive real slow on a 50 tooth sprocket and put put everywhere through down town city parts or tow a heavy load or live in hill city lol get a 14mm and your low end will pack a punch from the fast flowing fuel right of idle !! but your top end will suffer over 7,000rpm

the best over all carb for a stock motor is the NT with a high flow filter

the bet for a midrange ported and modded high comp motor would be the dellorto 15.5mm or the cns v3 the mikuni clone 15.5mm the dellorto is expencive but easy to set up and tune the cns v3 well some people toss it in the garbage cause they cant get it right . i love mine it is verry tunnable and i know it inside and out !

you got a super high comp race motor ??? well reed block and a 18mm mikuni or a 19mm dellorto phgb

 

[rogergendron1]

here are the 5 best carbs for our motors in order of size smaller first and preformance lower prefomer first

1 stock nt, works just fine up to around 7,000 rpm and gives gut wrenching torque in lower rpms
2 cns v3, this is a clone of the 16mm mikuni carb found on dirt bikes lie the yamaha pw80 it works awsome on a motor ported and polshed with a little head decking and a free flow exhaust, plenty of midrange power and some extra top end flow from the larger opening
3 dellorto 15.5mm this carb is easy to tune and can be run on anything from stock to all out racer. its an all around prefomer.
4 dellorto phgb 19mm, this is whats used on big boar race mopeds and requires a large port motor to flow fuel air correctly and needs a lot of tunning to get up and running but the pay off is an amazing fuel spitting monster carb
5 mikuni 18mm for top of the line racers who know how to tun a carb and have the motor to suck the fuel from it !

 

[rustycase]

IMO, VM Mikuni is a great carb.
rc

 

[neum5464]

All this is good info on carbs, but there is no discussion of exhaust... a carb swap while using the stock exhaust will do almost nothing except keep the engine cleaner. You cannot have greater flow when the air is coming in at a rate faster than the air going out. If you want to notice the power difference a better carb will offer you have to get rid of the stock exhaust (because it is designed for 4-stroke motors) and get something with an expansion chamber.

 

[rustycase]

64, can I kinda disagree with that???

I do agree a tuned expansion chamber is necessary to get the absolute most from a 2 cycle engine. However, with very few adjustable exceptions, tht power will be achieved in a rather narrow rpm band, usually very high speed.

What this will do is cause the engine to just about fall flat on it's face at low rpm, with only small improvement from that at mid-range.

Some of this low rpm power loss may be reclaimed by an increase in compression.

The stock chinagirl exhaust system is designed to be manufactured cheaply, and to reduce sound to imposed standards.
If a rider were to tamper with the muffler, removing some of the baffle material, and slightly enlarging the exit port, IMO, the best balance of power across the rpm range may be achieved.

Cleaning up the ports will help flow, and using a header length of 20" is also known to be beneficial, overall.

...just my opinion...
please get a 2nd opinion on anything I say!
Best
rc

 

[dodge dude94]

LOL Time for a threadjack!


I'm likely in the market for a new carb...stock NT from Dax or an RT?


Or should I go with a CNSV3 so I can use my top and needle and all my other stuff?

 

[rogergendron1]

i love the cns v3 !! others litteraly tos it in the garbage !!! hey if you dont want yours pm me and i will py the shipping to send it to me !!!

the cns is not for every one !!! you realy need to know how to tune a carb !!!!!

it does not work well with any stock motor ether so if your stock forget about buying it.

the cns v3 works best with the air idle cap removed to expose the mix screw, this makes the carb fully adjustable !! needle, pilot, main iar idle, and idle !!!
9you must grind extra slots in your needle to adjust it but thats easy)

it works its best as a high torque midrange carb and a little on the top rpm gain when your motor has the following...high comp head, free flow exhaust, moderate to heavy port work. if you meet those requirements and know a good amount about carb tunning you will find that given all thigs equal the cns will help make more torque and higher speeds than the nt due to it larger venturi size and over all jet design. it will produce more torque than the dellorto but the dellorto will beat it for speed and quickness of rev's becaus it has way better fuel atomization even though its the same size 16mm.

i would highly recomend the cns v3 if you know your stuff and plan on future modds, but dont expect to notice any differance between it and your current carb on a stock motor besides a lil quicker reving up and a higher rpms leading to slightly more speed.

if you dont know tunning go with the 16.mm dellorto sha clamp on, it only needs the main jet to be changed to tune the whole thing due to the jet designe !!! and its as large as the cns v3 so top speed will increase a few mph and rev speed will increase but that is all you will get out of it from a stock motor

size does not always matter sometime designe plays more of a roll for instance a 15mm walbro butterfly diafram carb will out preform practicaly all round slide carbs you could bolt to this motor !!!

 

[maniac57]

I'm going to have to agree with roger here...
The cns can work much better than stock on a modified engine.
And it is also much more adjustable and finicky. You really do need to know what each adjustment does and how to tune it correctly.
And yes, bolting it to a stock motor is a waste of cash and time.
In my opinion, the RT is by far the better carb for a stock engine being built and tuned by a newcomer to building and tuning the china girl engine.

 

[mapbike]

I like the NT and the RT carbs, I have a RT on a non ported BGF engine that has a Puch hi hi 50cc head with two head gaskets and a SBP expansion exhaust, it cruises at a nice comfortable 30-32MPH

I have a bike with a 36T rear sprocket with heavily ported jug on a dax balanced lower with MM shorty intake, Puch hi hi 70cc head, piston with tranfer and exhaust ramps ground in and a straight pipe free flowing exhaust, I'm running a well tuned NT carb on this engine and turning well over 8000 RPMs and can cruise at 42-45 MPH and have had this bike clocked at 47-48 MPH, its obvious that this engine runs out of carb at the high end of the RPM's, but I can testify for a fact from experience that with a balanced crank and the right amount of jug porting one can expect 40+MPH cruise speeds with an NT carb if the bike is set up right, I have a RT carb that I plan to put on this engine and see if that will possibly give a couple more MPH on the top end and I would like to have the same throttle response on this engine as I do with my other one that is running the RT, I'm gonna say for the average- light to moderately modified china girl engine, the NT or the RT dellorto Clone/or Dellorto SHA is probably the best bang for the buck and just plain works and is easy to get set up like others here have said.

Unless someone is just going crazy freaking all out on a China Girl engine with high end mods, anything bigger than the RT is just a waist of time and money.

From my personal experience the stock exhaust is a heap of junk no matter what you do to it, unless it's completely gutted, end cap removed and mounting flange is hogged out to it's maximum width for as good of a port match as possible, in my experience almost anything else out there is better unless it's an exhaust that still used the stock type highly restrictive muffler, a straight pipe with a round lawnmower muffler makes more power than the stock pipes do is the flange has some work to it.

Ive had stock pipes modified so that they would flow good enough for me to have the same top speed on the flat as a straight pipe, but the real difference in how the engine ran came when I needed to go up a hill, that is when the stock muffler would fall on it's face and the engine with a straight pipe an expansion pipe or with a mower muffler welder to the stock header pipe would shine way above, even a straight pipe that is to long will cause a power loss on the hills, these engines need to flow easily for them to make their best power and torque plain and simple.

Map

 

[rogergendron1]

I like the NT and the RT carbs, I have a RT on a non ported BGF engine that has a Puch hi hi 50cc head with two head gaskets and a SBP expansion exhaust, it cruises at a nice comfortable 30-32MPH

I have a bike with a 36T rear sprocket with heavily ported jug on a dax balanced lower with MM shorty intake, Puch hi hi 70cc head, piston with tranfer and exhaust ramps ground in and a straight pipe free flowing exhaust, I'm running a well tuned NT carb on this engine and turning well over 8000 RPMs and can cruise at 42-45 MPH and have had this bike clocked at 47-48 MPH, its obvious that this engine runs out of carb at the high end of the RPM's, but I can testify for a fact from experience that with a balanced crank and the right amount of jug porting one can expect 40+MPH cruise speeds with an NT carb if the bike is set up right, I have a RT carb that I plan to put on this engine and see if that will possibly give a couple more MPH on the top end and I would like to have the same throttle response on this engine as I do with my other one that is running the RT, I'm gonna say for the average- light to moderately modified china girl engine, the NT or the RT dellorto Clone/or Dellorto SHA is probably the best bang for the buck and just plain works and is easy to get set up like others here have said.

Unless someone is just going crazy freaking all out on a China Girl engine with high end mods, anything bigger than the RT is just a waist of time and money.

From my personal experience the stock exhaust is a heap of junk no matter what you do to it, unless it's completely gutted, end cap removed and mounting flange is hogged out to it's maximum width for as good of a port match as possible, in my experience almost anything else out there is better unless it's an exhaust that still used the stock type highly restrictive muffler, a straight pipe with a round lawnmower muffler makes more power than the stock pipes do is the flange has some work to it.

Ive had stock pipes modified so that they would flow good enough for me to have the same top speed on the flat as a straight pipe, but the real difference in how the engine ran came when I needed to go up a hill, that is when the stock muffler would fall on it's face and the engine with a straight pipe an expansion pipe or with a mower muffler welder to the stock header pipe would shine way above, even a straight pipe that is to long will cause a power loss on the hills, these engines need to flow easily for them to make their best power and torque plain and simple.

Map

yup all of this is true and thoughyour nt has a main jet and needle in it that is tunned right for your higher end bike i bet that same bike would see a lot more torque and top end (if your up to the tunning task ) with a cns v3 !!!!!

the dax rt is a clone of the dellorto sha 15mm i think and its a GREAT clone though the 16mm real dellorto is the way to go if you have the cash to toss at it ... i dont lol...all you have to do is swap the main jet and the carb tunnes itself !!!! richer or leaner....

now the dellorto pbgh is another story its like the rt or sha but it has proper air idle circut idle jet needle jet and main jet and is very difficult to tune for carb newbs !!!

if your a new and just want an all around good preformer that will hold up to years of use and handle all the upgrades and mods you can through at it go get a 15mm dax rt or a real 16mm delorto sha !!!! best carbs for the money for a guy who wants an easy tune and a great prfoming carb ! it will litteraly bolt on and go with noticable rev's and top end gain .



ohhh and i do gut the cat out of my black cat exhaust then extend the chamber 4 in and weld it back together then drill out the stock stinger to a big ol 1/2 in hole lol seems to add a whole lot more power !!! your right on the exhaust too

 

[rogergendron1]

the problem with the cns v3 i have is it needs to be tunned day to day diferently depending on the weather LOL !!!!!

i litteraly have to adjust the air idle circut and idle screw as the weather changes !!!! it just too sensitive !!!! wake up its cold out bike idles high .... adjust idle screw and air fuel mix ..... later on it gets warm bike idles low and dies rich on the 1/4 ... ahhh damn adjust screws all over again .... night time cold again ... guess what pull over adjust screws lol

the cns v3 is like a sensitve little girl with emotional problems, do not go dating her unless your in it for the chalenge !!!! lol lol lol lol i like her cause she's pretty and delivers the goods when happy !!!!

 

[mapbike]

yup all of this is true and thoughyour nt has a main jet and needle in it that is tunned right for your higher end bike i bet that same bike would see a lot more torque and top end (if your up to the tunning task ) with a cns v3 !!!!!

the dax rt is a clone of the dellorto sha 15mm i think and its a GREAT clone though the 16mm real dellorto is the way to go if you have the cash to toss at it ... i dont lol...all you have to do is swap the main jet and the carb tunnes itself !!!! richer or leaner....

now the dellorto pbgh is another story its like the rt or sha but it has proper air idle circut idle jet needle jet and main jet and is very difficult to tune for carb newbs !!!

if your a new and just want an all around good preformer that will hold up to years of use and handle all the upgrades and mods you can through at it go get a 15mm dax rt or a real 16mm delorto sha !!!! best carbs for the money for a guy who wants an easy tune and a great prfoming carb ! it will litteraly bolt on and go with noticable rev's and top end gain .



ohhh and i do gut the cat out of my black cat exhaust then extend the chamber 4 in and weld it back together then drill out the stock stinger to a big ol 1/2 in hole lol seems to add a whole lot more power !!! your right on the exhaust too

Ditto................!

Map

 

[dodge dude94]

Hmmmm. you guys have given me some food for thought here. I never thought of the V3 as being an actual performance carb. I've always just thought of it being the EPA-certified version of the V2. As for mods, I might be doing some piston and port mods this winter since I don't ride in the cold. I was going to get the RT from Dax but kinda shyyed away when I was it was 30 bucks.


I wonder if I can get my girl to get me the Dax RT and a pipe for my birthday....hmmmm

 

[rogergendron1]

Hmmmm. you guys have given me some food for thought here. I never thought of the V3 as being an actual performance carb. I've always just thought of it being the EPA-certified version of the V2. As for mods, I might be doing some piston and port mods this winter since I don't ride in the cold. I was going to get the RT from Dax but kinda shyyed away when I was it was 30 bucks.


I wonder if I can get my girl to get me the Dax RT and a pipe for my birthday....hmmmm

it is a clone of a mikuni preformace carb ... it meets epa reg because they block off the air idle screw with a cap and give the needle only 1 possition

all you do is pop the cap off and grind out new slots for the needle or repace the needle with older ver cns or mikuni one

then its a fully tunnable 16mm mikuni clone, fair warning though its dificult to tune......

go with the dax rt the dellorto clone if easy breasy is what you want ...

 

[dodge dude94]

it is a clone of a mikuni preformace carb ... it meets epa reg because they block off the air idle screw with a cap and give the needle only 1 possition

all you do is pop the cap off and grind out new slots for the needle or repace the needle with older ver cns or mikuni one

then its a fully tunnable 16mm mikuni clone, fair warning though its dificult to tune......

go with the dax rt the dellorto clone if easy breasy is what you want ...

Gotcha.


Looking at carbs now, the NT is good for low end as it's a smaller throttle opening. My low end is pretty good with my CNS, which is kinda big compared to the NT. And the RT is about the same size as the CNS right? So no harm, no foul in going with a big bore carb, right?

I can get a NT with cable for $17.99 from rose326a on ebay, and the Dax RT is $29.99 and doesn't have a cable.