Carby Carburetor - help with my grubee skyhawk 2 stroke 66cc

[Old Skool]

Oldskool...
this is one of those cases where "you're right about everything and i'm just another moron."
sorry dude but i know what i'm talking about, and i know that the potential for a fire with starting fluid getting sprayed around an intake manifold is little to none.
unless you are a total idiot and totally soak the motor with the stuff, there can't be a fire.
the starting fluid will get sucked into ANY tiny air leak and get burned INSIDE the combustion chamber.(this is why i said use a tiny amount in short bursts and concentrate on one are at a time).
how in the he-- can you find an air leak with a flashlight?
if you have a double over lapping flange and the air leak is around a corner, how in the heck can the light find it's way out?
a flashlight can't turn corners.
90% of the typical hardware store o-rings are made for plumbing (water) and are just rubber.
I'm telling you that they will not hold up to to gasoline.
do some research and you'll find that out for yourself.
I don't give 2 craps if you grew up in an oil field town or on an oil rig.
That doesn't mean jack to me and how can that make you the king of o-ring knowledge?
i've been building engines since i was 12 years old, i've built drag cars, street cars and motorcycles. My dad has been a mechanic for over 50 years and he has owned his own shop for over 30 years. i learned everything i know by growing up watching him, and working for him. I've been working on , restoring, rebuilding all things mechanical for well over 30 years and there really isn't anything out there that i can't fix or diagnose. anyone can replace parts but not everyone can diagnose a problem without being wrong.

all it takes to use starting fluid is a little common sense.
you wouldn't go and dump a 5 gallon can of gas onto a fire would you? no...because that would be dumb and your common sense would tell you not to do it.
same thing applies with starting fluid. don't go overboard and don't soak down the whole engine, and it'll work just fine with no danger.

Motorpsycho:

Well ... I apologize if I offended you. That was not my intention. I do not wish to engage in some type of cross-country ****ing contest.

As previously mentioned - I prefer to err on the side of caution. If your stated method works for you, stick with it. As for me, I have found some of my methods to work well for me, without the potential hazards of being severly burned.

As a side note ... Some of my techniques in building firearms and reloading of ammunition may work well for me, but I would never advise another person to do some of the things that I do. Yeah, I know, that doesn't qualify me as being an expert in anything. I agree! The oilfield comment was intended to be somewhat "tongue-in-cheek". I regret that you did not see the humor in it.

I have been twisting bolts and wrenching engines since about 1960, and as a kid I set a speed record at a local drag strip with one of my own engines. But, like the oilfield comment - that ain't got nothing to do with this. Years later, I earned an upper degree from a major technical university - which also has nothing to do with Skyhawk troubleshooting. I have probably riden, raced, and rebuillt motorcycles since before you were born.

Setting all of the chest thumping aside, I regret that we had a misunderstanding.

A high entensity flashlight with a flexible stem can find its way into a lot of different crooks and crannies - and light does bend in a reflective environment. If the room is dark, you might be amazed at what you see.

You might also remember that my original advice to the other patron was to "NOT introduce anything in the intake system that might be drawn into the engine". I suppose in that, we both agree, so let's agree to disagree on some of the other points.

Blessings to you, brother.

Old Skool

 

[motorpsycho]

yeah i'll buy that and i see your point. lets definitly not turn this into a peeing match...that's useless here.
everyone has their own form of troubleshooting and i guess you can use what works best for you, and i'll use what works best for me.
yeah i have owned a few drag cars with engines that i built run in the 10.50 - 10.80 range at the dragstrip, but like you said, that has nothing to do with this.
so i agree to disagree with you, and we can leave it at that.
No hard feelings...

 

[Dyran]

thanks for the advice guys and I didnt use a rubber o-ring i made an o ring out of gasket material. i will try to find the leak, i just havent had much time on my hands between work and, me being a teenager, and all social events.

 

[Old Skool]

thanks for the advice guys and I didnt use a rubber o-ring i made an o ring out of gasket material. i will try to find the leak, i just havent had much time on my hands between work and, me being a teenager, and all social events.

Dyran:

In time, you will find your problem. This may not help you much, because the build is still fairly new, but after a while, you will begin to get a "feel" for what ails the little gas sipping critter. That generally comes with experience, and no one can "explain" it to you.

Don't fixate on one thing, because you may be trying to fix something that ain't actually broke. I think your original post had to do with having to use the choke to get the throttle to respond. To me, that suggests that the carb is too lean. In simple terms, it is getting too much air for the correct ratio of gas. (Or) putting it another way - not enough fuel - for the amount of air being taken into the combustion chamber.

That is sometimes a delicate balance, but it is what makes the carburetor work properly.

This choke design is a little different than some other small engines. Rather than restrict the air flow, it actually increases the fuel flow. Same principal, but a different method of enriching.

I had similar issues as you, but in my case, I had more than one problem. I had an air leak - plus a shortage of fuel. The vacuum leak was due to air being pulled into the top of the carburetor, around the throttle plate. After fixing that, I found a lot of improvement, but it was still a tad too lean at mid range, and could not be completely corrected by the adjustment screws on the side of the carb.

So ... keeping that in mind ... I enriched the fuel slightly by moving the gas needle from the #2 to the # 3 position. Bingo! With a little tweaking of the side adjustment screws, she purred like a kitten.

It is possible that you have a float level issue. That is sometimes a little tricky to get right, but it can be resolved. It is possible that the engine is angled to such a degree that the carburetor will not function properly. Which, by the way, will create a float level problem. If the angle is too far off, the fuel bowl on the carb will not fill properly (or) may fill too much.

I hope that makes sense. Look at the total picture, and as I previously stated - don't try to fixate on one potential issue - which may not be the real problem.

Keep us posted.

Old Skool

 

[Dyran]

could it be that i am not putting enough gas into the gas tank, because i only actually filled the tank once and that was before i switched bikes, and before it was running perfectly fine, so what i am thinking based off what Old skool said about there not being enough fuel to the amount of air that is being taken in. maybe, because i do not have a full tank there is less pressure pushing the fuel into the carb, therefore there is not enough fuel to air.???? im gonna try filling my tank and riding it, i will tell you guys if it works.

 

[motorpsycho]

nope that has nothing to do with it. what he's talking about is the mixing ratio of air to fuel that takes place inside the carb. there is an adjustment screw for that on the side of the car.
the amount of gas in the tank won't make one bit of difference as to how it runs, unless the tank if totally empty.
I still think that you may be using the choke backwards and what you think is off, is actually on.
if you have the choke on and you think it;s off, the engine will bog, stall out and run very bad because it's giving the engine too much gas.
a normal style choke restricts the air flow going into the carb. it allows more less air to get in the carb (a rich air-fuel mixture) for easier starting.
the choke on your carb doesn't restrict the air, it adds more gas when it's on which gives a rich air - fuel ratio as well.
the difference is that your choke does not restrict air, it adds gas to the mixture.
so i'm thinking that you may have the choke on when you think it's off.

 

[Dyran]

nope that has nothing to do with it. what he's talking about is the mixing ratio of air to fuel that takes place inside the carb. there is an adjustment screw for that on the side of the car.
the amount of gas in the tank won't make one bit of difference as to how it runs, unless the tank if totally empty.
I still think that you may be using the choke backwards and what you think is off, is actually on.
if you have the choke on and you think it;s off, the engine will bog, stall out and run very bad because it's giving the engine too much gas.
a normal style choke restricts the air flow going into the carb. it allows more less air to get in the carb (a rich air-fuel mixture) for easier starting.
the choke on your carb doesn't restrict the air, it adds more gas when it's on which gives a rich air - fuel ratio as well.
the difference is that your choke does not restrict air, it adds gas to the mixture.
so i'm thinking that you may have the choke on when you think it's off.

but when i have the choke on to about half way (where i get the most power out of the engine) i can't idle, but if i turn it off it can idle. I think i found the leak i used your method with the starting fluid to find it, i just need to try and get a better seal on the o ring, i think i need a thicker one.

 

[Old Skool]

but when i have the choke on to about half way (where i get the most power out of the engine) i can't idle, but if i turn it off it can idle. I think i found the leak i used your method with the starting fluid to find it, i just need to try and get a better seal on the o ring, i think i need a thicker one.

Geez ~ it is very difficult to diagnose an engine problem when you're half way across the country. I will certainly agree the former comment that the level of fuel in the tank has nothing to do with your problem. As long as the carb is receiving fuel, the level in the gas tank is insignificant. The fuel to air ratio is determined within the carburetor, not the fuel tank.

The misunderstanding of the choke position is a very legitimate point. When the choke is "off" (not deployed) the cable linkage should have little to no tension. When the choke is "on" (applied), the choke cable should be tight and pulling the brass choke plunger up into the upper chamber. Try moving the choke lever (on the handlebar, or wherever you mounted it) and at the same time using your other hand to feel the movement of the cable on the top of the carb. When the cable tightens, you should be able to feel the increase in tension. When the choke is off, the cable should be relaxed.

Another point - which may not be the way "everyone" does it - but it works for me. First, tighten each external carb adjustment screw down - and COUNT THE TURNS - and write them down on a piece of paper if necessary. That way, you will know what your current settings are, in the event you want to go back to that setting.

After both screws are turned to the right and closed ... open each adjustment screw 1/2 turn. That should be enough to allow the engine to start. Crank the engine, ride it a minute or two, to ALLOW THE ENGINE TO WARM UP! Then stop your bike and leave your engine running.

If it is idling too fast, slightly open the screw on the right a little bit at a time. Maybe 1/8 turn or so, and carefully listen to the tone of the engine. The right screw (while looking at the carb) serves as the idle adjustment. Opening that screw allows a little more air to be introduced to the ratio. At some point, you should be able to achieve a proper idle.

Be sure that the choke is NOT deployed - and try riding the bike again. If the fuel is "too lean" or maybe "too rich", and does not properly respond to the throttle, then stop and tweak the "left" adjustment screw a little. There is no good way to explain the difference between too lean and too rich, but I will give it a shot. If it is too lean, it will be like the engine just quit running. You will have no response, because it is mostly sucking air. If the carb is too rich, you will commonly hear the motor make a "EWWWWW" noise. It is getting fuel, but not enough air.

You should be able to find a "sweet spot", where the engine idles and responds to the throttle. If continued tweaking of the left screw does not give you good results, you will need to move onto something else. This method will help to determine if the problem is an external adjustment issue.

You might get lucky and find that the real problem was simply an incorrect adjustment. After some trial and error on that and you still have to use the choke to get the throttle to respond, I will say that you are not getting enough fuel into the combustion chamber. (too lean)

One way to increase the fuel is to move the clip setting on the carb plunger to a richer setting. I think the "default setting" is in the second notch, which may be too lean for you. Move the clip to the #3 position. That might then fix your problem.

I do understand that some of the things that I have tried to explain may sound like a lot of Greek to you, so I found a web page that has photos and descriptions of the CNS carb. It may not look exactly like yours, but it should be pretty close.

http://kcsbikes.com/topic.asp?TOPIC_ID=121

The link may not appear as HTML, so you may have to copy and paste it into your browser bar.

Anyway ... if one of us other guys was nearby, we could probably having you running in a few minutes. But, that ain't the case, so you'll probably just have to attend the University of Hard Knocks, until you get it figured out. Every day is a learning experience. At some point, it will begin to "click".

Good luck,
Old Skool

 

[Dyran]

Geez ~ it is very difficult to diagnose an engine problem when you're half way across the country. I will certainly agree the former comment that the level of fuel in the tank has nothing to do with your problem. As long as the carb is receiving fuel, the level in the gas tank is insignificant. The fuel to air ratio is determined within the carburetor, not the fuel tank.

The misunderstanding of the choke position is a very legitimate point. When the choke is "off" (not deployed) the cable linkage should have little to no tension. When the choke is "on" (applied), the choke cable should be tight and pulling the brass choke plunger up into the upper chamber. Try moving the choke lever (on the handlebar, or wherever you mounted it) and at the same time using your other hand to feel the movement of the cable on the top of the carb. When the cable tightens, you should be able to feel the increase in tension. When the choke is off, the cable should be relaxed.

Another point - which may not be the way "everyone" does it - but it works for me. First, tighten each external carb adjustment screw down - and COUNT THE TURNS - and write them down on a piece of paper if necessary. That way, you will know what your current settings are, in the event you want to go back to that setting.

After both screws are turned to the right and closed ... open each adjustment screw 1/2 turn. That should be enough to allow the engine to start. Crank the engine, ride it a minute or two, to ALLOW THE ENGINE TO WARM UP! Then stop your bike and leave your engine running.

If it is idling too fast, slightly open the screw on the right a little bit at a time. Maybe 1/8 turn or so, and carefully listen to the tone of the engine. The right screw (while looking at the carb) serves as the idle adjustment. Opening that screw allows a little more air to be introduced to the ratio. At some point, you should be able to achieve a proper idle.

Be sure that the choke is NOT deployed - and try riding the bike again. If the fuel is "too lean" or maybe "too rich", and does not properly respond to the throttle, then stop and tweak the "left" adjustment screw a little. There is no good way to explain the difference between too lean and too rich, but I will give it a shot. If it is too lean, it will be like the engine just quit running. You will have no response, because it is mostly sucking air. If the carb is too rich, you will commonly hear the motor make a "EWWWWW" noise. It is getting fuel, but not enough air.

You should be able to find a "sweet spot", where the engine idles and responds to the throttle. If continued tweaking of the left screw does not give you good results, you will need to move onto something else. This method will help to determine if the problem is an external adjustment issue.

You might get lucky and find that the real problem was simply an incorrect adjustment. After some trial and error on that and you still have to use the choke to get the throttle to respond, I will say that you are not getting enough fuel into the combustion chamber. (too lean)

One way to increase the fuel is to move the clip setting on the carb plunger to a richer setting. I think the "default setting" is in the second notch, which may be too lean for you. Move the clip to the #3 position. That might then fix your problem.

I do understand that some of the things that I have tried to explain may sound like a lot of Greek to you, so I found a web page that has photos and descriptions of the CNS carb. It may not look exactly like yours, but it should be pretty close.

http://kcsbikes.com/topic.asp?TOPIC_ID=121

The link may not appear as HTML, so you may have to copy and paste it into your browser bar.

Anyway ... if one of us other guys was nearby, we could probably having you running in a few minutes. But, that ain't the case, so you'll probably just have to attend the University of Hard Knocks, until you get it figured out. Every day is a learning experience. At some point, it will begin to "click".

Good luck,
Old Skool

We're not really halfway across the country, and i know i dont have the choke backwards, im not a total retard, im just a little retarded. and thanks for the link it helped a lot, now i realize what my problem is (i think it is the same problem you were having with your bike, Old Skool.

 

[Dyran]

If i am going through all this trouble trying to get this carb to work properly, would it be easier for me to just buy a different style of carb, if so could you recommend which one i get