Rusty gave you good advise, that is the overflow tube, so if you have fuel coming out of it then the needle valve is probably not closing properly. If this is new behavior then I would suggest you clean the carb (needle valve) and that should take care of it, and make sure you float isn't taking on gas....
CNS carb working great....
- Thread starter nightcruiser
- Start date
It's the first time I've added gas for a while, wonder if just venting the gas tank could have caused it ?
Venting a gas tank will not cause a carburetor to overflow.
Take the carburetor apart and carefully clean it, paying special attention to the float needle valve.
While it is apart check the float height setting and correct it if necessary.
Take the carburetor apart and carefully clean it, paying special attention to the float needle valve.
While it is apart check the float height setting and correct it if necessary.
Anybody had experience with the CDI going bad suddenly ? I had it running great for weeks, shut it off as normal yesterday, today no fire.
Yes, I have heard of that happening, but this is kind of the wrong thread to ask about that, being a thread about the carb....
Search the forum for "no spark" and you will probably find better info, and/or start a new thread with an appropriate topic so people will find your question and help you out. In this thread your question is kind of hidden.....
PS Could be your cdi, wire, boot, problem with your magneto etc causing no spark, but I would prefer not to go into that discussion here in this thread about CNS carb tuning....
Great read NT Thank you for your efforts you have helped so many folks. I did just like you said "I'm gonna toss this thing on fresh out of the box before I have a chance to screw anything up on it"
Well I did just that and after a few sputters and a clank , clank or two I hopped off to see every possible spot that could leak gas was leaking and what wasn't leaking gas was sucking air That's when I found your thread here!.My 4 yr old Nephew could prob. make a carb out of cardboard and screen that would leak less than this thing did today
I have one question NT I hear of CNS v/ 1 & v~2 Now mine doesn't have that brass vent nipple on the top I see everyone else has.
Mine is sealed off from the factory. I'm guessing this is the version 2. Ive pretty much made up my mind I'm going back to my stock, never leaks, always true, starts every time, I want it too NT.
I'm gonna use the fancy choke cable set up from the CNS on the NT choke lever So I don't have to do the ole reach around & down any more. I think I will take the CNS and see what a Louisville Slugger will do to it with one Big Papi home run swing .[/I]
Last edited:
hey just wanted to clear something up with the needle valve. you say the pointed side is supposed to go up in the tube? i ask cause i have rebuilt bike carbs before for like dirtbikes and what not and i thought the pointed side is always against the float?...
if im wrong will some one get back to me asap?
i want to know if they had it in there backwards from the factory? or was it in there right
AWSOME THREAD BY THE WAY!! ALOT OF HELP!!
if im wrong will some one get back to me asap?
i want to know if they had it in there backwards from the factory? or was it in there right
AWSOME THREAD BY THE WAY!! ALOT OF HELP!!
Last edited:
The float valve is called a needle and seat valve. The pointy (needle) end always goes towards the seat which is up inside the "tube". Speaking of carbs in general, the other end of the needle portion of the valve can be all sorts of shapes ranging from a plain looking smooth rounded end, a mushroom end where a groove just underneath the head of the mushroom fits in between the center gap of a two prong fork looking piece attached to the float arm, and the most common these days is a small spring loaded plunger that slides up inside the body of the needle.
Also, most modern needles have a rubber tip on them. The pointy end is actually made of a gas resistant rubber to help seal better against the seat and reduce wear on the seat/ needle seal which promotes longer life and a higher resistance to damage caused by debris getting stuck up in there.
Sadly, the common China Girl carb does not have this modern feature.
Also, most modern needles have a rubber tip on them. The pointy end is actually made of a gas resistant rubber to help seal better against the seat and reduce wear on the seat/ needle seal which promotes longer life and a higher resistance to damage caused by debris getting stuck up in there.
Sadly, the common China Girl carb does not have this modern feature.
Last edited:
hey I was running into a few issues with my cns today
now the other day I drained the gas tank, and bowl for storage but decided to ride the bike today
I kept running into problems
basically on WOT runs it would run fine, then slowly start to slow down some
so I flip the fuel lever then it may start to run fine may not
So I had to work the enricher lever about half way then it would come alive for a little while, then I could turn the lever off
happened quite alot today
So ive remembered reading something about this in the past using the choke/enricher to get it to run properly
but I cant remember what the fix was
Im quite certian the jetting is fine, and im sure it wasnt seizing
just seemed like a lack of fuel if the enricher made it instantly better
if anything im too rich plug is a dark brown, not a tan
I even went to 23:1 from 32:1 just to be leaner and have been running that since I jetted the cns carb so its had at least 1 gallon of 23:1 in it
I was also wondering if it was because I filled the tank too much and on the very first ride fuel was vibrating all out the cap
I was wondering if that kept the air from getting in, as my cap fits super tight anyways
its really hard to pull out
ALso the needle clip was all the way up high(lean) but ive rode it that way alot and it worked fine
But I put it back to center then rode it more and had those same bogging issues
so I dont think it was the needle
I took the carb apart, maybe the pilot could of had something in it, there was alot of silt in the bowl
So after the cleaning I was riding it very hard around the neighborhood, all seems good but I wont know until I ride it again back in the same place
I was thinking it was the float but its still at the correct level, and seems to move freely
I may of been using a filter I never tried before but its the same type I used when it was working just a new one. If it was oiled it was 2 weeks ago I dont even see any oil on it dont think thats an issue
so what could it be
gas cap not venting properly?
pilot jet partially clogged, silt in the bowl?
dont think I have any air leaks, I had sealant on the intake and carb mount and all bolts were tight, none have been taken off since it was mounted a while ago
I did drill one micro hole in the cap, just to vent it for sure
now the other day I drained the gas tank, and bowl for storage but decided to ride the bike today
I kept running into problems
basically on WOT runs it would run fine, then slowly start to slow down some
so I flip the fuel lever then it may start to run fine may not
So I had to work the enricher lever about half way then it would come alive for a little while, then I could turn the lever off
happened quite alot today
So ive remembered reading something about this in the past using the choke/enricher to get it to run properly
but I cant remember what the fix was
Im quite certian the jetting is fine, and im sure it wasnt seizing
just seemed like a lack of fuel if the enricher made it instantly better
if anything im too rich plug is a dark brown, not a tan
I even went to 23:1 from 32:1 just to be leaner and have been running that since I jetted the cns carb so its had at least 1 gallon of 23:1 in it
I was also wondering if it was because I filled the tank too much and on the very first ride fuel was vibrating all out the cap
I was wondering if that kept the air from getting in, as my cap fits super tight anyways
its really hard to pull out
ALso the needle clip was all the way up high(lean) but ive rode it that way alot and it worked fine
But I put it back to center then rode it more and had those same bogging issues
so I dont think it was the needle
I took the carb apart, maybe the pilot could of had something in it, there was alot of silt in the bowl
So after the cleaning I was riding it very hard around the neighborhood, all seems good but I wont know until I ride it again back in the same place
I was thinking it was the float but its still at the correct level, and seems to move freely
I may of been using a filter I never tried before but its the same type I used when it was working just a new one. If it was oiled it was 2 weeks ago I dont even see any oil on it dont think thats an issue
so what could it be
gas cap not venting properly?
pilot jet partially clogged, silt in the bowl?
dont think I have any air leaks, I had sealant on the intake and carb mount and all bolts were tight, none have been taken off since it was mounted a while ago
I did drill one micro hole in the cap, just to vent it for sure
So this is what I have
#72 drill bit main jet
Went riding again after the bike sat for a few hours and the high speed bog came back. I had to use the enricher lever then it ran fast.
So I put the needle down 1 past center (richer)
When going 3/4 throttle or a hair more it runs fast, then full throttle it slows down just a touch. Barely noticeable. From the little I know and alot I forgot I thought that meant lean.
So I opened up the main jet to a #70 drill bit.
Now it has even power through the throttle twist, I kept the needle that one setting richer
Now up this hill I didnt have to pedal the last 15 feet it went up it just fine
Which makes sense because today the hills were murder on my bike while others with the stock carb were flying past me
I even have 4 teeth larger rear sprocket, but I am dragging a cen clutch with all that extra rotating mass I expect to slow a little
So maybe it was the new filter just flowed a touch different then the exact same type I had on there before
Will test tomorrow again to be sure the jetting does someting
#72 drill bit main jet
Went riding again after the bike sat for a few hours and the high speed bog came back. I had to use the enricher lever then it ran fast.
So I put the needle down 1 past center (richer)
When going 3/4 throttle or a hair more it runs fast, then full throttle it slows down just a touch. Barely noticeable. From the little I know and alot I forgot I thought that meant lean.
So I opened up the main jet to a #70 drill bit.
Now it has even power through the throttle twist, I kept the needle that one setting richer
Now up this hill I didnt have to pedal the last 15 feet it went up it just fine
Which makes sense because today the hills were murder on my bike while others with the stock carb were flying past me
I even have 4 teeth larger rear sprocket, but I am dragging a cen clutch with all that extra rotating mass I expect to slow a little
So maybe it was the new filter just flowed a touch different then the exact same type I had on there before
Will test tomorrow again to be sure the jetting does someting
SDCruiser,
Wow!
A whole lot of things going on there!
Overall, IMO, it seems likely there was a bit of debris affecting the performance of the carb. It may have passed it through, it may still be there, or there may be more on the way.
Seems to be causing intermittent, on again, off again problems.
The only thing you can do is work your way through the problem, a step at a time.
You mentioned a filter above, but I can't recall you said specifically that you had a fuel filter in the line. They are necessary, primarily because these jets and other internal passages are so small, and easily clogged, or at least influenced by debris.
Best to focus on one thing at a time, and don't introduce new variables.
You did not mention what specific mix oil you are using, but IMO, if you are using a common mix oil, you should be at a 32:1 ratio and stay at that mix until your particular problems are resolved.
A chinagirl spits back out the carb sufficiently that you shall never need to oil the air cleaner foam. It might even become excessively clogged over a period of time, but that probably hasn't happened yet. So don't focus on that.
Only other thing that occurs to me at this time is that in spite of the 48T rear sprocket you now have? you may be expecting too much performance from the little motor. Hills will always be hills!
Good luck
rc
Wow!
A whole lot of things going on there!
Overall, IMO, it seems likely there was a bit of debris affecting the performance of the carb. It may have passed it through, it may still be there, or there may be more on the way.
Seems to be causing intermittent, on again, off again problems.
The only thing you can do is work your way through the problem, a step at a time.
You mentioned a filter above, but I can't recall you said specifically that you had a fuel filter in the line. They are necessary, primarily because these jets and other internal passages are so small, and easily clogged, or at least influenced by debris.
Best to focus on one thing at a time, and don't introduce new variables.
You did not mention what specific mix oil you are using, but IMO, if you are using a common mix oil, you should be at a 32:1 ratio and stay at that mix until your particular problems are resolved.
A chinagirl spits back out the carb sufficiently that you shall never need to oil the air cleaner foam. It might even become excessively clogged over a period of time, but that probably hasn't happened yet. So don't focus on that.
Only other thing that occurs to me at this time is that in spite of the 48T rear sprocket you now have? you may be expecting too much performance from the little motor. Hills will always be hills!
Good luck
rc
I have about 4 gallons of fuel through the engine maybe more.
1 gallon 16:1
1 gallon of 23:1
2 gallons 32:1
and over 1/2 to 1 gallon of 23:1
I know what to expect out of the bike, how it runs
I think I have enough time on it
I had only changed the fuel to get the jetting leaner at the time, adding more oil make it leaner
easier then dicking with the jet
Yes I have another filter, a nice glass one. It has alot of sediment in there. Even my fuel line because its ran almost horizontally has a small trail of black gold sitting in it. Im guessing all this is from the tank.
When I took out my jet the bowl still had little bit of black gold in it, even though I had just cleaned it couple hours ago. But im willing to bet there has always been that stuff in the bottom.
At first I was thinking it was the gas tank filter clogged since I had drained the tank through the line the other day
but now I dont think it was that, or the gas cap. Even though when we were out in the hot sun I could hear the fuel sucking air through the gas cap. Like its not venting properly
Thats why I drilled a micro hole in the cap
and I am doing one thing at a time
the only change was the filter but its the same exact type
and only rode it a little not enough to notice anything bad
first was the carb cleaning, hole drilled in gas cap
second was the needle to richer
third was the needle to leaner
fourth was the upjet, and needle to center
I just dont want to drive it in the dark with cooler weather
I like to tune it in the same weather I ride in, just incase the slight difference messes with it
Well, it does sound like you are on track to a solution!
Most likely it was crud in the fuel line or tank...
Gosh, that's a first for me, to find someone who could actually hear the fuel tank drawing a vacuum! Must be a huge petcock you got on there!
Still, IMO, adjusting your burn by the amount of mix oil in the fuel doesn't seem like a good practice, to me. I suppose there might be folks who would do it.
Good luck
rc
Most likely it was crud in the fuel line or tank...
Gosh, that's a first for me, to find someone who could actually hear the fuel tank drawing a vacuum! Must be a huge petcock you got on there!
Still, IMO, adjusting your burn by the amount of mix oil in the fuel doesn't seem like a good practice, to me. I suppose there might be folks who would do it.
Good luck
rc
sitting around in the sun engine off you can hear the noise
not when its running
when I jetted the overly rich cns carb, even though everyone here says they come lean it was easier to change the oil mix. I think I tried 3-4 drill bits
most all I had to solder in the jet, all done at night
I was done racing around back and forth all night trying all needle positions
I dont have the patience for 2-3 day jetting. Ive done that in the past and am done with that.
Plus I wanted a more oil overall, we ride these hard on and off road so I want more lube and since before it was rich anyways why not add more oil takes care of 2 things at the same time
I just see no point in jetting it leaner, only to use 32:1 oil mix
I had the exact same top speed between those 2 mixes, I even used a gps to get my top speeds on the same piece of road in front of my house. So oil ratio gave no performance gains
So what about having to use the enricher to get the boost and get back to top speed
since it allows more fuel in, doesnt that make sense then I needed to upjet
or would I need to use the enricher the entire time to say a upjet is what needs to be done?
I have read this in the past, and im searching now for it but I just cant remember what the normal fix was when someone had to use the choke to get it to run properly
Back when I thought I had the carb dialed in anytime I used the enricher, on purpose just to test it would instantly loose alot of speed
and doing that enricher with my left had almost throws me off the bike from the fast loss of speed
It did that same thing tonight after I upjetted
where earlier today it would of just given me a boost or power or no change
since it allows more fuel in, doesnt that make sense then I needed to upjet
or would I need to use the enricher the entire time to say a upjet is what needs to be done?
I have read this in the past, and im searching now for it but I just cant remember what the normal fix was when someone had to use the choke to get it to run properly
Back when I thought I had the carb dialed in anytime I used the enricher, on purpose just to test it would instantly loose alot of speed
and doing that enricher with my left had almost throws me off the bike from the fast loss of speed
It did that same thing tonight after I upjetted
where earlier today it would of just given me a boost or power or no change
Yes, a change in the dampering of the air filter will change the tuning of the carb. Think of it like this, the piston creates a suction, the dampering of that suction by the air filter forces the carb to pull fuel through the tiny hole of the jet. If you damper the filter more there is more suction on the jet, plus less air, so richer mix. If you lessen the dampering on the filter you have more air and less fuel, so a leaner mix. If you change the filter type, or even when the filter gets oily and clogged she will likely run different...
probably the filter
just cant imagine that as the old and new are exactly the same
sure I could of oiled both of them differently but I did the oiling the same exact way
But who knows the quality of them or what they are made of
This is why I should of rode it more when I put the new filter on, but im at the point where I dont ride the bike anymore because I got so many other toys to mess with
But I will make sure its setup correctly tomorrow so when I do put it away for a while it will be all set
I pulled out a old stand up scooter I didnt use for a few months
had to put another style filter on that one because I stole the old one off of it for a dirtbike
and that I had to change the high speed screw 1/2 leaner because it would bog out and die trying to accelerate from a dead stop
Now it runs great, but I was expecting something to change with an entire different designed filter
just cant imagine that as the old and new are exactly the same
sure I could of oiled both of them differently but I did the oiling the same exact way
But who knows the quality of them or what they are made of
This is why I should of rode it more when I put the new filter on, but im at the point where I dont ride the bike anymore because I got so many other toys to mess with
But I will make sure its setup correctly tomorrow so when I do put it away for a while it will be all set
I pulled out a old stand up scooter I didnt use for a few months
had to put another style filter on that one because I stole the old one off of it for a dirtbike
and that I had to change the high speed screw 1/2 leaner because it would bog out and die trying to accelerate from a dead stop
Now it runs great, but I was expecting something to change with an entire different designed filter
So what about having to use the enricher to get the boost and get back to top speed
since it allows more fuel in, doesnt that make sense then I needed to upjet
*there is really no 'boost' available to a two stroke engine without a turbo, or supercharger. An expansion chamber designed properly for an engine will send a pressure wave back into the cylinder, though. Perhaps this is what you are thinking of?
If you feel an increase in power and speed, when running at WOT and engaging the enrichen circuit, your main jet is too small and should be drilled to a larger size. *
or would I need to use the enricher the entire time to say a upjet is what needs to be done?
*If your enrichen circuit must be on all the time for something closer to suitable running it would indicate the carb is totally gunked up, the needle valve is restricted, or the fuel delivery system is somehow plugged. (Which would include a vacuum developing in the tank from improper venting.)
I have read this in the past, and im searching now for it but I just cant remember what the normal fix was when someone had to use the choke to get it to run properly
Back when I thought I had the carb dialed in anytime I used the enricher, on purpose just to test it would instantly loose alot of speed
and doing that enricher with my left had almost throws me off the bike from the fast loss of speed
It did that same thing tonight after I upjetted
where earlier today it would of just given me a boost or power or no change
*A properly tuned engine, running at operating temperature, would normally drop in rpm when the enrichen circuit is engaged, while running along at operating speed. When idling, that should kill the engine.
*The problem here is typical chinagirl CNS design flaw.
They are NOT a good carburetor and it is extremely difficult to tune them properly.
I'll bet there are many people who have been able to do it adequately, but I have not yet heard of someone who can tune one to the degree that a mikuni or dellorto may be dialed in precisely for maximum power through the operating rpm range.
*Things creep up on me slowly.
It does seem as though you have considerable experience.
I am thinking the problem here is that you are failing to take notice that the HT/chinagirl is a marginal product and has very little quality.
The overall design is antiquated, the engineering shabby, metalurgy and castings always questionable, and the production, assembly, and quality control are always atrocious. Integrity is lacking.
Keeping all that in mind, they are a heck of a lot of fun, and may deliver service, on that scale, for a very modest pricetag.
The Al.Fisherman pre-assembly teardown for inspection, and small parts replacement can be of significant value for every new buyer.
IMO you should purchase an inexpensive NT carb, jet it suitably, and run it 'til the other typical chinagirl discrepacies arise.
The NT design is superior, and simpler.
Good luck
rc
since it allows more fuel in, doesnt that make sense then I needed to upjet
*there is really no 'boost' available to a two stroke engine without a turbo, or supercharger. An expansion chamber designed properly for an engine will send a pressure wave back into the cylinder, though. Perhaps this is what you are thinking of?
If you feel an increase in power and speed, when running at WOT and engaging the enrichen circuit, your main jet is too small and should be drilled to a larger size. *
or would I need to use the enricher the entire time to say a upjet is what needs to be done?
*If your enrichen circuit must be on all the time for something closer to suitable running it would indicate the carb is totally gunked up, the needle valve is restricted, or the fuel delivery system is somehow plugged. (Which would include a vacuum developing in the tank from improper venting.)
I have read this in the past, and im searching now for it but I just cant remember what the normal fix was when someone had to use the choke to get it to run properly
Back when I thought I had the carb dialed in anytime I used the enricher, on purpose just to test it would instantly loose alot of speed
and doing that enricher with my left had almost throws me off the bike from the fast loss of speed
It did that same thing tonight after I upjetted
where earlier today it would of just given me a boost or power or no change
*A properly tuned engine, running at operating temperature, would normally drop in rpm when the enrichen circuit is engaged, while running along at operating speed. When idling, that should kill the engine.
*The problem here is typical chinagirl CNS design flaw.
They are NOT a good carburetor and it is extremely difficult to tune them properly.
I'll bet there are many people who have been able to do it adequately, but I have not yet heard of someone who can tune one to the degree that a mikuni or dellorto may be dialed in precisely for maximum power through the operating rpm range.
*Things creep up on me slowly.
It does seem as though you have considerable experience.
I am thinking the problem here is that you are failing to take notice that the HT/chinagirl is a marginal product and has very little quality.
The overall design is antiquated, the engineering shabby, metalurgy and castings always questionable, and the production, assembly, and quality control are always atrocious. Integrity is lacking.
Keeping all that in mind, they are a heck of a lot of fun, and may deliver service, on that scale, for a very modest pricetag.
The Al.Fisherman pre-assembly teardown for inspection, and small parts replacement can be of significant value for every new buyer.
IMO you should purchase an inexpensive NT carb, jet it suitably, and run it 'til the other typical chinagirl discrepacies arise.
The NT design is superior, and simpler.
Good luck
rc
the only reason im using this carb is its a better performer then the stock
since I use a cen clutch with a stock carb properly jetted the bike would vibrate accelerating
with the cns its smooth, almost like it puts out a little more power from a dead stop
both carbs top speed was about the same, nothing to drastic of a change
and the throttle response with the cns feels better
since I use a cen clutch with a stock carb properly jetted the bike would vibrate accelerating
with the cns its smooth, almost like it puts out a little more power from a dead stop
both carbs top speed was about the same, nothing to drastic of a change
and the throttle response with the cns feels better
So now with all this new knowledge about this carb. I'll try again!
I too am minutes away from ordering the NT... But You have inspired me with new hope
Thank you for your time, thought and post...on this carb. very useful.
I too am minutes away from ordering the NT... But You have inspired me with new hopeThank you for your time, thought and post...on this carb. very useful.