stock/nt carb rejetting: how much lower than the stock 70 have you ever had to use?--or heard of someone else using?

[BIG BOBBY]

my stock NT carb is running rich, even after downjetting all the way to a 66, lowering the float level, dropping the needle To max lean, and unrestricting my stock muffler.

so now I am buying the "fine tuning jets-low 60's" from bicycle motor works. this pack of jets goes all the way down to a 60.

my question is:
has *ANY* body ever had to go all the way down to a 60? --or even lower???? (----because now im getting concerned about this carb being defective.... or something.)

bicyclemotorworks only has jets to a 60. no smaller. im also worried about trying to doctor a defective carb and going too lean.

but the exhaust drippage, the dark plug, and the four-stroking are all telling me that this 66 jet I have in there now is STILL too rich, and therefore I need an even smaller jet.

ALL my seals, and ALL my gaskets and connections are tight and right.

BTW,.....im ONLY referring to the china girl stock NT carb.

 

[Deleted member 27811]

Just go down one at a time until you nail it. You'll now when its right. You want it to 4 stroke a little until it gets hot and clears. I'm using a #68 in a Dellorto 16-16. You might want to look at a Runtong 15-15. (clone Dellorto) They work. Don't forget to refer to a sea level guide to find out where you are where you live.

 

[FNTPuck]

I have never needed less than a 68 but I am at sea level. Can't imagine a 60 being too big...you sure its rich (4stroking/sputtering up top) and not lean (lack of power, sounds "hollow" under load)

 

[BIG BOBBY]

nope its def. rich. 4 stroking, smoke, exhaust drippage,..dark plug....crappy mileage,.....its obviously rich. ---and im about 25 feet above sea level.

well,..the low 60's pack of jets will be here soon

 

[Deleted member 27811]

nope its def. rich. 4 stroking, smoke, exhaust drippage,..dark plug....crappy mileage,.....its obviously rich. ---and im about 25 feet above sea level.

well,..the low 60's pack of jets will be here soon

You can try soldering the one that's in it, then micro drill it to the # you can make use of. There is a lot on here about that very thing. (carry on)

 

[BIG BOBBY]

yeah,..i totally read that,...and im sure it would work. but these jets are already OTW.

but---

if the 60 is still too rich (I hope not)--I will be buying the micro bits at harbor freight. no other choice at that point except to buy a new NT. this never, ever happened to me before. stock NT's are usually on,...or real close,....like yours with a 68.

im still wondering if anyone has ever had to go as low in jet size for a stock NT as im about to.. --would be re-assuring as hell right now

 

[gary55]

Something else is wrong. Is there some obstruction in the exhaust? Is the spring seated right in the slide of the carb, or the pacman clip missing or under the Cclip? I'm at 5400 ft and rarely need to go below 66. Does the carb leak if you leave the gas on? does the float have liquid in it? Do you have another carb you can try on it?

 

[Greg58]

I've never bought jets I solder and drill them, I'm running a .026 jet which is a #73 drill bit on a 48cc at about 1k above sea level, I can't believe a 66cc would need that.

 

[BIG BOBBY]

dude I checked everything. I even drilled out extra holes in the muffler cap and cut off the inner exhaust spout tube. air just flies through. the carb is also set up right,...the pacman clip is Over the c clip/needle clip, the spring is also a-ok. no gas leaks anywhere,...float level is good.

---did you say .026 jet??? what is that equal to in relation to,....you know,.... numbered jets? aka,...70,...65,....etc --that sounds tiny. much smaller than a 63 which is what I think im gonna try next.

the first thing i checked was obstructions in the intake/exhaust. I re-checked again. free-flowing stock air filter too. this thing ran rich the moment I started it for the first time and hasnt stopped.

every single telltale sign of rich.

i would also like to state that at wot she runs great up to a certain rpm and then 4-stroke city.

****and non stop 4-stroking at any other throttle position other than wide open.****

real good power at wot until about 5-6k rpm and then 4 stroking.

it seems like it's very close to running right,...right now.

when these low60's jets get here ill update for sure.

all im asking here is are low 60's jets ever used on a 66cc?

 

[BIG BOBBY]

I've never bought jets I solder and drill them, I'm running a .026 jet which is a #73 drill bit on a 48cc at about 1k above sea level, I can't believe a 66cc would need that.

--so it is unheard of for a 66cc to require a jet in the low 60's? (lower than 65?)