Fuel needle sticking

[(Ian)]

After adjusting my valve needle a few times it started getting harder for everything to *click* back together. I tried lubricating it a bit with some motor oil but that didn't help. At first, I'd just have to start unscrewing the cap (tang, is it called?) and it'd click in on its own. Now it won't, and I've no sooner got it put back together than it sticks again. This results in no tension on the throttle, because the spring is compressed.

Is this common? It could be:
-the housing sticking: maybe, but it doesn't appear dirty or damaged
-the spring: more likely, since it looks a little crooked. Not much, but definitely crooked
-the throttle cable: seems a tad frayed and might be catching on something.

 

[AussieSteve]

You need to learn a few correct terms. Have a read here:- NT Carb Tuning Basics

Sounds like you're talking about a sticking slide. Don't oil it.
It is a common problem.
The spring won't be causing it. If the throttle cable is frayed, replace it.

Are you sure you're aligning the groove on the side of the slide with the locating pin?

Sometimes, the slide will stick only when the top cap is tightened. Mine used to do this. I fitted a fibre washer in the top cap that fixed the problem.

You might need a new slide or carb.

 

[motorpsycho]

I have a feeling that this is another case of the "mis-aligned slide slot, to the pin in the carb." again.
this is SO common, this is the first thing that i suggest people check when they say that their throttle is sticking or the slide won't move.

 

[AussieSteve]

Yep, more often than not. (Deja-vu)
Otherwise, the body/slide distortion problem comes second.

 

[(Ian)]

It's definitely aligned. Mine's the kind with an idle slot as well. Would I fit the fibre washer between the cap and the spring then? I was thinking it might be possible that the carb is out of round, possibly from over tightening. It doesn't look like it though.

 

[AussieSteve]

It's definitely aligned. Mine's the kind with an idle slot as well. Would I fit the fibre washer between the cap and the spring then? I was thinking it might be possible that the carb is out of round, possibly from over tightening. It doesn't look like it though.

They all have the chamfered slot for the idle screw.

The spring still fits inside the fibre washer.
Pics attached.

My carb body went out of round when the cap was tightened, but returned to normal when the cap was off.
If your's is tight all the time, check closely for small dings on the slide body. It doesn't take much to cause drag. As mentioned, you might need to replace the slide or carb.

 

[motorpsycho]

yes, but the idle screw slot is shorter than the pin slot. if you have the idle screw slot, lines up with the pin, the slide will bind up and stick.

 

[(Ian)]

Hey thanks for your help, especially Aussie with the diagrams. I'm going to pick up a fibre washer that fits today and see if that will make a difference. Looking at the carb, I don't really see anything out of round. In the well itself (the housing that the needle/housing assembly slides into) it looks like there's a line that kind of sticks out...could it be a mold line or is it supposed to be there? It's at the area where the threading stops, on the inside of the carb.

 

[AussieSteve]

A washer will only help if the slide sticks when the cap is tight but doesn't stick if it's loose or removed.
Not sure about the mold line. A close-up pic would help.