Carby my carb issues
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KenM
Member
Hi all, I am trying to get my carb setup right too. A stock 66cc setup.
With the needle set in the top notch, it is to lean, runs like a champ but can not get a good idle, either to fast or to slow and stalls. And the spark plug is clean, no trace of carbon at all.
In the second notch it is to rich, runs good, idle good, spark plug is a little black with carbon.
Is there a way to fine tune it in the middle of the two notches? Or just run it on the rich side? Thanks in advance! Ken.
Keep looking up!
With the needle set in the top notch, it is to lean, runs like a champ but can not get a good idle, either to fast or to slow and stalls. And the spark plug is clean, no trace of carbon at all.
In the second notch it is to rich, runs good, idle good, spark plug is a little black with carbon.
Is there a way to fine tune it in the middle of the two notches? Or just run it on the rich side? Thanks in advance! Ken.
Keep looking up!
D
Deleted member 12676
Guest
these carbs are not truly tunable, period
get a good one
get a good one
KenM
Member
Thank you Mr. Crassius! I will have to try that out.
I should of thought of that myself. I used to do set the float level on the Britsh motorcycles I had all the time, and then their were two of them. Then you had to syn. then. Ok , thanks again! Keep looking up! Ken.
I should of thought of that myself. I used to do set the float level on the Britsh motorcycles I had all the time, and then their were two of them. Then you had to syn. then. Ok , thanks again! Keep looking up! Ken.
D
Deleted member 12676
Guest
yeah but it affects the jetting throughout the whole range equally
HeadSmess
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a few tricks.
start at the beginning.
basic carb circuits. (NT specifically)
the idle mixture is controlled by the small wedge "cutaway" at the BOTTOM of the slide. not to be confused with the IDLE SLOT thats also at the bottom of the slide.
a flat bottom slide is RICH. as the angle of this cutaway increases...they get leaner.
so thats the IDLE circuit. normally, something you completely IGNORE unless you really know what youre doing...because the only way to go richer than the stock slide, is to make one. applying a file makes them leaner.
(though you can file the base flatter, i guess. but that will also affect where the needle sits in the jet, which would then need raising blah blah )
theres no pilot screw, so no need to worry about the idle side at all.
the NEEDLE and the clip on it controls HALF throttle. mids. raising makes it richer, etc.
it DOES NOT affect the top end.
the only thing affecting WOT is the size of the jet. and the lil hole in the spraybar that the needle slides into.
if it DIES at FULL throttle...its too lean. get a bigger jet.
if it slows down but still makes power at full throttle...it is too rich. get a smaller jet.
i dont like this term "bogging" as some people think its when it dies at full throttle...other people think its when it just doesnt want to reach full rpm. and therefore, its hard to tell what someone means.
now, just for this purpose, i keep an ngk 4 heat plug. they stay clean.
throttle chops. start at the full throttle part. then half throttle, and finally idle if you want to bother. warning. get the idle bordering on too lean, and the smallest air leak will cause problems. why its best to overlook the idle part.
after all this, performing good plug chops (warm the engine up properly or they will be false readings... as jag says, twostrokes (all engines really) start rich. and the rich condition gets progressively worse as they warm up. whereas a lean mix will richen slightly as the engine warms up. youre finding the line between being able to start easily, near maximum power when running, and longevity...)
if the plugs coming out black...its rich.
if its white, its lean. if its just starting to show some colour, perfect.
then you can go back to a more standard plug, like a 6 or so... which should go tan or brown but never black...
and of course, the plug chop is not perfect... its a guide. the heat range of the plug, and the oil (content) affect the reading. the real test is does it FEEL more powerful?
start at the beginning.
basic carb circuits. (NT specifically)
the idle mixture is controlled by the small wedge "cutaway" at the BOTTOM of the slide. not to be confused with the IDLE SLOT thats also at the bottom of the slide.
a flat bottom slide is RICH. as the angle of this cutaway increases...they get leaner.
so thats the IDLE circuit. normally, something you completely IGNORE unless you really know what youre doing...because the only way to go richer than the stock slide, is to make one. applying a file makes them leaner.
(though you can file the base flatter, i guess. but that will also affect where the needle sits in the jet, which would then need raising blah blah )
theres no pilot screw, so no need to worry about the idle side at all.
the NEEDLE and the clip on it controls HALF throttle. mids. raising makes it richer, etc.
it DOES NOT affect the top end.
the only thing affecting WOT is the size of the jet. and the lil hole in the spraybar that the needle slides into.
if it DIES at FULL throttle...its too lean. get a bigger jet.
if it slows down but still makes power at full throttle...it is too rich. get a smaller jet.
i dont like this term "bogging" as some people think its when it dies at full throttle...other people think its when it just doesnt want to reach full rpm. and therefore, its hard to tell what someone means.
now, just for this purpose, i keep an ngk 4 heat plug. they stay clean.
throttle chops. start at the full throttle part. then half throttle, and finally idle if you want to bother. warning. get the idle bordering on too lean, and the smallest air leak will cause problems. why its best to overlook the idle part.
after all this, performing good plug chops (warm the engine up properly or they will be false readings... as jag says, twostrokes (all engines really) start rich. and the rich condition gets progressively worse as they warm up. whereas a lean mix will richen slightly as the engine warms up. youre finding the line between being able to start easily, near maximum power when running, and longevity...)
if the plugs coming out black...its rich.
if its white, its lean. if its just starting to show some colour, perfect.
then you can go back to a more standard plug, like a 6 or so... which should go tan or brown but never black...
and of course, the plug chop is not perfect... its a guide. the heat range of the plug, and the oil (content) affect the reading. the real test is does it FEEL more powerful?
Last edited:
Isn't the jet size depend on the altitude where you are located. I'm not saying not to use a #66 jet but you may have to try different sizes.
Spare_Parts
Well-Known Member
Couple of years late...
So what! It’s never too late to learn something. I’m sure these carbs still have the same issues they had a couple of years ago. Whether it’s a new or old post obviously many people like me read these posts to increase their knowledge, isn’t that why you wrote the posted in the first place.
Thanks for your input.
