I have been having an issue with a "motocross" bike. I can run it just fine for about 3-4 days(30 mins each day) and than, after that, it stops running. I clean the carb, and it will run again for that period of time. Although, today I cleaned the carb, and that did not fix it. I don't know what to do to fix this. The bike is a Honda XR 80cc FRAME with an Italika 125cc ENGINE(Kick Start, no battery) on it, essentially a mixed bike. The CARB is not from that engine. I also have to run it on full choke all the time when running it, if I put it on half it will die quite easily. Here are some things that should not be the problem...

-The gas tank vent is not clogged
-Gas flows just fine out of the tank
-I installed a new fuel line
-There are no kinks in the fuel line
-I installed a new gas filter
-There is a spark, electrical stuff is fine

It seems when I open the carb, that it has like some brown residue on the housing. I clean that up each time. I don't understand why it doesn't work. It has to be something with fuel, fuel flow, pressure, or the carb.
Can someone please help me out here.
Any help would be appreciated
Here is a pic of the bike: Motocross Bike - Album on Imgur

Thanks!

 

Running only on full choke tells me you have a vacuum leak or incorrect/plugged jets.

I would also verify that the stalling is fuel related and not anything else.

What do the plugs look like? They will tell the fuel mixture story.

 

What do you mean by vaccum leak? The connector from the carb to the engine has a fair hole in it which I have covered with bike tire rubber and wire. Do I need to replace that part? The spark plug is standard, it sparks each time I check it. It may be rusted slightly, but mostly a grey color. The gap is fine, and I think the piston does not hit the tip of it

 

Any place where air can get in other than through the carb is an unmetered air leak. When you put on the choke, you are reducing the air supply to compensate for the extra air that's getting in there.

Read the plugs. The tips will tell you how the mixture is and what's burning in there.

This is all basic carb stuff that applies to pretty much all vehicles.

 

Okay. I will take a look. I could send you a pic of it as well. Usually it just has carbon deposits from the explosions