Help with CARB

Greg58

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May 1, 2011
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I haven't used that carb, I keep mine simple and use the standard nt carb. I've tried the cns2 carb that was to replace the nt, suppliers were sending the cns in kits in 2010, the carb itself is fairly good it's the rubber/plastic bushing that inserts into the carb as a gasket or spacer to fit the larger cns to the standard intake that fails.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Why do you think it's trash(ed)?
From the sound of it, your running rich. Find out why.
Throwing parts at a problem is just a waste of money.
 
Jun 29, 2020
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Westerly Rhode Island
I initially had issues with mine (identical, different seller), before I even put it on the intake I changed the stock jet to a 66, and one of the reasons I was getting poor (throttle) response was the throttle return spring wasn't properly seated on the slide. Couple things about this particular carb threw me off was the lack of a needle, and the cable being beside, rather than through the spring like the NT, and most other 2 stroke carbs. Trick to these carbs is loosing the neck provided on the top of the carb, I used the one from the NT, getting as much slack out of the cable as you can by adjusting BOTH ends of adjustment, i.e., throttle and carb end, and then adjusting idle screw AND cable to get proper idle, and if running rich, just add less oil-to-gas than you are without seizing the motor. These things are what I like to call 'Tinker-Toys', and if you don't like to tinker? Get a 4 stroke.
 

Greg58

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May 1, 2011
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Adding LESS oil will make a 2 stroke run RICHER.
What Joe is talking about is fuel to air richer not oil to gas richer. Since oil is thicker than gas, when you add oil to gas the mixture is thicken. When air is drawn through the carb it draws the fuel from the bowl, if you add less oil the fuel is thinner so more fuel is drawn into the air stream passing through the carb. Its like drinking a milk shake through a straw vs a soft drink.
 
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Jun 29, 2020
6
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60
Westerly Rhode Island
Adding LESS oil will make a 2 stroke run RICHER.
Maybe my terminology is incorrect, but with every 2 stroke engine I've ever dealt with, if it was running rich, I'd mix less oil-to-gas...making the premix 'leaner'. That's just the way me and everyone I know who's ever dealt with them regarded that. In terms of air/fuel, that's what we called it, and that's what sucks about these NT, and even the 'HP' carbs, all you can do with them is adjust idle, and if I want different air/fuel, I re-jet...that's what I meant, lean-out the premix, and go with a colder plug, that's what I've always done, with no issues. Since mine's broken-in, I'm going 40:1 (from a 32:1 break-in mix) with Lucas and a NGK B5HS plug, B6 if those are too cold, and with that #66 jet in the HP carb, it should run nigh-on perfect, at least in my experience...
 

Greg58

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May 1, 2011
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I run the Lucas as well, Its been good for mine. One motor I got in August of 2011 that is on my black bike that's my avatar, the only thing that has happened to it was a blown base gasket last spring.
 

Greg58

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May 1, 2011
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Maybe my terminology is incorrect, but with every 2 stroke engine I've ever dealt with, if it was running rich, I'd mix less oil-to-gas...making the premix 'leaner'. That's just the way me and everyone I know who's ever dealt with them regarded that. In terms of air/fuel, that's what we called it, and that's what sucks about these NT, and even the 'HP' carbs, all you can do with them is adjust idle, and if I want different air/fuel, I re-jet...that's what I meant, lean-out the premix, and go with a colder plug, that's what I've always done, with no issues. Since mine's broken-in, I'm going 40:1 (from a 32:1 break-in mix) with Lucas and a NGK B5HS plug, B6 if those are too cold, and with that #66 jet in the HP carb, it should run nigh-on perfect, at least in my experience...
No problem, we're not picking it's just we have a lot of different experience levels here and some people may get the two types mixtures confused. What I do is settle on a oil to fuel ratio then jet the carb to get the best performance. I solder and drill my jets, this has been best for me.
 
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FOG

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Mar 3, 2019
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I know it seems backwards but when you add more oil it displaces some of the fuel in the resulting mixture. Less fuel is leaner.

The effect is very small tho. More a point of technicality than anything else.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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16:1 vs 40:1 is more than twice as much gasoline.

I've done experiments with the two- lighting it on fire. The 40:1 lights and burns a lot easier/more ferociously.
 
Jun 29, 2020
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60
Westerly Rhode Island
Well, as long as the cranks getting oil (I've run dirt bikes at 50:1 oil/gas without issue), at the end of the day isn't that what you want? As long as I've dealt with them (I'm 60), if I ran ANYTHING richer than 32:1 (oil-to-gas), I'd make sure to bring spare plugs, because I would need them on long rides (lotta tree-filled, slow-going trails here in the N.E.), so a lean gas/oil was kinda necessary for that kind of riding if lazy like me, and not wanting to rejet every time, so I mix for the conditions, and pretty much 'set-and-forget' the carbs air/fuel issues, if so equipped. So with this HP carb, which is new to me, from what I've read regarding them, and personal experience, however limited, I'm finding that tuning these carbs requires jetting for conditions (#66 at sea level), Premix ratio, cable-play, spark plug type (B5HS) and the single idle screw they both have, dictates how well the engine works from idle, all the way up...in my experience. Sorry for the book, but maybe I do have the terminology backward, just that by the philosophy I've always went with described above, I've never had any issues. I had my first real motorcycle (1974 Honda CR250M Elsinore) for almost 5 years, and only changed the top end once when I first got the bike, running it using what I know to get this Chinese crap dialed in. And I say 'crap' in the nicest of ways, as it IS a good running little engine, just needs more tweaking in places, simply because of what it is...cheap fun. RPM out...
 

Greg58

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May 1, 2011
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I think we all try to apply what we have learned from quality Japanese made bike engines to these, some will work. I had at least one dirt bike till I reached 55, at one time I owned 3. I had a little 180 Yamaha try to take me out in 08, 71K hospital bill on a $500 bike.