NT Carb Slide Turning

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Cyclin

Cyclin

New Member
Jul 4, 2011
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California
Hey Guys,

So I recently had some trouble with my first gen NT carb and was able to discern that the slide was not properly aligned and was coming down to rest on top of the idler screw, causing high-revs and flooding.

I am having the same issue again, and I noticed something. With the air filter off, I watch through the back as I install the slide. I make sure to watch that the slide installs straight and is not turning. I then turn the idler screw in and out and watch the slide rise and fall as I adjust. So I know when first installed the slide is in the correct position, with the idler screw slanted side resting on the idler screw, or else the adjustments would show no effect.

So I turn the throttle, and as I release, the slide sets down on top of the pin again, leaving it way too far open. Is the slide rotating when I pull the throttle? That's what is seems like, and after a few throttle pulls I can see that the slide has rotated enough for me to see the slide slot that is supposed to be opposite the idler screw.

What could be causing the slide to rotate while installed in the carb? Do I need to adjust my cable where it meets the throttle? If so, should I give it more slack or less?

Thanks for all your help :) This forum is great, I learn something new every break-down haha

.duh.
 
Cyclin

Cyclin

New Member
Jul 4, 2011
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California
I think it may be the locator pin opposite the idler screw. Looks like it is flush to the inside of the carb but protrudiing slightly on the outside. Will post back if this fixes it... So from the outside I pushed it back in with a micro screwdriver.


Boomb shaka-laka. That did it. I can now see the carb slide moving back to its original position when I disengage the throttle. So as it turns out my entire issue from the get-go was the locator pin had been pushed too far out of the carb :)
 
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2door

2door

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Sep 15, 2008
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Littleton, Colorado
Cyclin, that pin has to be the problem. If it is there and aligned with the long slot in the barrel there is no way the barrel can rotate. It is rare but I have seen one NT carb that was missing the guide pin.
Let us know what you find.

Tom
 
Cyclin

Cyclin

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Jul 4, 2011
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2door said:
Cyclin, that pin has to be the problem. If it is there and aligned with the long slot in the barrel there is no way the barrel can rotate. It is rare but I have seen one NT carb that was missing the guide pin.
Let us know what you find.

Tom
Click to expand...
Yup that did it. Turn out it had gotten pushed (maybe from vibrations?) too far out of the carb and wasn't keeping the slide aligned.
 
crassius

crassius

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Sep 30, 2012
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often, that pin will get pushed out by someone forcing the slide in backwards
 
Cyclin

Cyclin

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Jul 4, 2011
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California
crassius said:
often, that pin will get pushed out by someone forcing the slide in backwards
Click to expand...
Ahh, so its possible it was user error, and that I did it to the locator pin myself the first time I re-assembled the carb incorrectly. That makes a lot of sense, thanks :)
 
C

CDBrandon82

New Member
Apr 10, 2017
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Fort Gordon, GA
Thank you so much for posting this! I am still working out the kinks on my first build, and I have the same problem. When I took out the slide, it looked like the piece had broken off, but it is good to know that it may just be pushed in. I hadn't even thought to check. I just assumed it had broken. I cannot wait to get home to see!

I already have an upgraded carb on order, but I hated to have to tell the wife. This has been item number 500 on the glitch list since I started this, and my wife's patience is dwindling LOL! Thank you so much!
 
2door

2door

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Staff member
Sep 15, 2008
16,302
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Littleton, Colorado
CDBrandon82 said:
Thank you so much for posting this! I am still working out the kinks on my first build, and I have the same problem. When I took out the slide, it looked like the piece had broken off, but it is good to know that it may just be pushed in. I hadn't even thought to check. I just assumed it had broken. I cannot wait to get home to see!

I already have an upgraded carb on order, but I hated to have to tell the wife. This has been item number 500 on the glitch list since I started this, and my wife's patience is dwindling LOL! Thank you so much!
Click to expand...
Brandon,

Don't be too quick to replace that NT carb with an "upgraded carb". Unless you've done extensive modifications to your engine the kit supplied NT will provide you with all the fuel/air your engine can use and any aftermarket carburetor might be a disappointment to you if you're expecting a noticeable performance gain.

There is a lot of good information here regarding the pros and cons of so called, 'performance carburetors' for the Chinese 2 stroke. I'd suggest you do some reading and research before wasting your money.

Tom
 
C

CDBrandon82

New Member
Apr 10, 2017
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Fort Gordon, GA
Tom,

Thanks for the heads up! I wasn't really looking for any performance increase, but just better functionality. I've had quite a few problems with this carb since I got it, and most of it is due to structural shortcomings. The one i found seems to be a little more mechanically sound in its design. Perhaps I just got a bad NT. Nontheless, I want to keep the NT on there until the engine is completely broken in. I haven't done any mods to the engine, but would like to in there future as I become more experienced with this thing. I did find some rubber gaskets for the intake, any thoughts on that?

Thanks again!

-Chris
 
ZipTie

ZipTie

Active Member
Jan 8, 2016
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Mpls Mn
I've had the carb slide locator pins too short when I've gotten them, they are just press fit in . I will tap them out longer so the slide wont turn. I always check them before install. Other than that these simple NT carbs are fairly dependable.
 
ZipTie

ZipTie

Active Member
Jan 8, 2016
750
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Mpls Mn
Rubber gasket? Are you referring to the o ring for the carb to manifold that one can add or some carbs come with? Or the intake manifold to engine gasket? The o ring can help most of the time. and sometimes they cause air leaks by not allowing the carb to slide on far enough onto the intake manifold and then they leak at the side slots.
 
C

CDBrandon82

New Member
Apr 10, 2017
12
0
0
Fort Gordon, GA
ZipTie said:
Rubber gasket? Are you referring to the o ring for the carb to manifold that one can add or some carbs come with? Or the intake manifold to engine gasket? The o ring can help most of the time. and sometimes they cause air leaks by not allowing the carb to slide on far enough onto the intake manifold and then they leak at the side slots.
Click to expand...
Yes, the O-Ring from the manifold to the carb. Ok, so it will have to be a trial and error thing then? What I am learning is that there is not always a "one size fits all" solution to these engines. Thanks for the info!

-Chris
 
crassius

crassius

Well-Known Member
Sep 30, 2012
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USA
I never recommend an o-ring there unless the carb has a plastic insert to hold it in place - dug more than one of those rings out after they got sucked in on a bike with nt-style carb.
 
crassius

crassius

Well-Known Member
Sep 30, 2012
4,032
158
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USA
yeah, I'm just a repair shop for these and all I see are the fails (and I see a lot of them)
 
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