Keep in mind that this carb. and atv ran pretty good just 5 months ago with just these jets.
Here is a pic of my jets

 

Ok. This guy here is actually two pieces. The main jet unscrews from this. May want to go ahead and do that to make sure your main jet is actually clear.

 

So what is best way to unscrew it? Gently put it in a vise? Ive never seen it come apart. Is it a common right hand thread?

 

The main jet should simply take a flat head screwdriver. Does yours have a slit across the top?

THen, just hold the other part with a wrench. It's got 6 point on the shaft.

Here's what the main jets look like.

Main Jet

 

Cleaned main jet, no difference.

Vexing because it just ran fine 6 months ago

 

Ok, so I found the vid on youtube. It starts and idles, but as soon as you give it gas, it falls on it's face. The jets are clean.

Here's kinda how that carb works. When you give it throttle, the upper diaphram acts off the vaccuum of the motor, and pulls the needle upward. That needle is the one that goes into the cylinder that the main jet screws into. The one you just took apart. If that needle does not move up, then fuel would not be allowed to come up thru the main jet, and it would fall on it's face like that. I would make sure that its put back together properly - the needle should move upward with that diaphram and I would also make sure the diaphram does not have any holes or tears in it. Also, make sure when you put it back together that the top cap seals the diaphram down correctly.

 

Oh, and I strongly recommend you adjust your valves, especially if you've never done one on this machine.

I don't know if this video is worth a crap, but just run a search in youtube for a gy6 or 150 valve adjustment.

 

Thanks ron. Its very hard to tell if needle is moving, it is not adjustable on this carb. Is there some way to test this?

I will try to do the valve adjustment thing.

Please keep the great advice coming

 

Ron can you post the video about the needle

 

Not sure if you can see this, but if you take off your air filter, see if you can see the slide go up when you give it throttle - with it running. The needle pulls up with the slide, but most likely you won't be able to see the needle.