NT carb questions.. what is what ???

[abefroman]

Ok, I've got an NT carb. there's a brass screw with spring sticking out the side of it. there's also an adjustment at the top of the carb where the throttle cable goes in. there's also an adjustment for the cable at the end of the metal tube where it goes into the throttle handle.

so, what exactly are all of these and how do I adjust them properly ? A buddy of mine says that the brass screw with the spring on it that sticks out of the side of the carb is the fuel air mixture screw. I told him he's wrong and it's the idle screw. I'm pretty sure I'm correct. Now, I understand the basics of how these carbs work. I used to restore british cars with SU carbs. The only fuel air adjustment that you can make is either to screw in a new jet, or move the clip at the top of the needle to another position.

I'm pretty sure I'm correct about that, but please enlighten me if I'm not.

Now, what is the cable adjustment at the top of the carb for and how should I adjust it ?

what about the cable adjustment at the throttle handle ?

anyone ? please help.

cheers

 

[2door]

Yes, you are correct about the idle speed screw and the internal workings of the NT.
It is a simple carburetor and in my opinion the best choice for a stock or slightly modified engine.

The cable adjustments are just that. They give you the ability to adjust the movement of whatever they are controlling. Typically you'll just screw the one at the carb all the way in and never have to use it. The one on the twist grip throttle can be used to fine tune if needed. Once the throttle is installed you can check the action of the carb slide by looking into the throat and twisting the grip to check if you have a full range of movement, up and down. The idle speed screw simply blocks the slide from closing all the way and sets your idle rpm by keeping it slightly open.

Hope this helps a little.

Tom

 

[abefroman]

yep. that's what I thought. a quick google search resulted in this...very good..

http://www.motoredbikes.com/showthread.php?24867-NT-Carb-Tuning-Basics


what's confusing is that I have been able to minimized "4 stroking" (at wot) by fiddling with the idle screw and the cable screw. very odd. theoretically they shouldn't have any effect at all.

 

[2door]

First question: How many miles/gallons of fuel have you burned? The Chinese 2 stroke needs to see at least two hundred, three is even better, before they start to perform well. They don't break in easily. Don't worry too much about 4 stroking until you get some miles on that little engine.

Also what fuel to oil ratio are you using? Disregard the kit instructions that might tell you to mix at 16:1. That has been proven to be too much oil. 24:1 is a better choice moving down to 32:1 after break in.

And no, the idle speed screw has no effect on how the engine runs above idle. However if the cable isn't adjusted correctly it could prevent the slide (barrel) from opening completely.

Tom