Engine Wont Run Unless Partially Choked

[motor_bike]

Worked perfect from the factory. Went to jail for 6 months and it was out in the weather unprotected.

It starts and runs, but with lower power, and the engine doesn't sound right. I worry if I keep using it, I'll cause permanent damage.

I've taken the carb apart several times, looking for debris, varnish, etc... and found nothing. Pulled the jet out and it was clean. Put black RTV on partially damaged intake manifold gasket and no improvement.

The engine won't hit on full choke, but there's a perfect spot around 3/4 choke where it will start firing, but it dies almost immediately unless you push the choke to about 2/3. It has to be perfect. Too little or too much and it runs badly, no power, and eventually dies.

Any help?

 

[Chainlube]

Take your air filter off and take a peak inside the throat, is the slide all the way to the bottom?

 

[motor_bike]

I took the carb off and left the throttle linkage attached. The black cylinder is up about 1 to 2 mm's, and no way to push it down lower.

Is it supposed to be all the way down?

 

[DAMIEN1307]

I took the carb off and left the throttle linkage attached. The black cylinder is up about 1 to 2 mm's, and no way to push it down lower.

Is it supposed to be all the way down?

Yes...The black barrel slide inside the carburetor cylinder can only go in just one way if you want it to work...You will notice a groove that travels all the way up and down on the barrel...That groove is there to fit itself on a little protruding 'nub' on the inside of the carby, you will put your finger in the cylinder and feel that nub on the right hand side of the carburetor that nub needs to be inside that groove in order for the slide to go fully up and down freely.

 

[Chainlube]

I took the carb off and left the throttle linkage attached. The black cylinder is up about 1 to 2 mm's, and no way to push it down lower.

Is it supposed to be all the way down?

Before you go any further, review the pictures at the start of this thread.

Carby - NT Carb Tuning Basics

A few basics on the Happytime NT Carburetor:- Some pics identifying the basic parts:- Float Bowl Gasket Also see srdavo's NT Carburetor Assembly Pics for a bit more info. Brief Description Of Operation The NT side-draught carburetor operates by drawing air into the air...

motoredbikes.com

1 to 2mm is about right for the opening at the bottom of the slide, you should need full choke to get it started when it's cold. If it won't run without the choke, then you have an air leak.

 

[motor_bike]

Yes...The black barrel slide inside the carburetor cylinder can only go in just one way if you want it to work...You will notice a groove that travels all the way up and down on the barrel...That groove is there to fit itself on a little protruding 'nub' on the inside of the carby, you will put your finger in the cylinder and feel that nub on the right hand side of the carburetor that nub needs to be inside that groove in order for the slide to go fully up and down freely.

It slides just fine, and it's all the way down.

Now what?

 

[Chainlube]

It slides just fine, and it's all the way down.

Now what?

Adjust the idle screw in some until the slide is up a bit from the bottom.

 

[motor_bike]

Okay, I've done that and the engine still won't run unless it's mostly choked.

 

[Chainlube]

Okay, I've done that and the engine still won't run unless it's mostly choked.

OK, with the engine running, get a spray bottle with some water in it and mist around your carb to intake area and then the intake to cylinder area. If it stalls out that is where the leak is at.

 

[motor_bike]

Okay I did the opposite of that and used starter fluid to see where it sped up. There were several areas around the carburator that were pulling in the starter fluid:
1) linkage for throttle control on top of carburator
2) seems like the bowl gasket is leaking too. Also there is a defecting the metal of the bowl (piece missing during casting)
3) back side or carburstor there is a brass plug where I think fuel air adjustment would be on a different model. Either the brass plug is leaking or the starter fluid is running down and getting sucked in at the carburator bowl.

Should I just buy another carb? They're $12.00 on eBay.