Replacing the vacuum line will help, if that's the problem, but sometimes the diaphragm in the petcock gives out and doesn't respond to the vacuum. All you need to do is remove the tank, replace the fuel line with some tubing on the petcock so fuel can run into a bucket, turn the tank dial to ON and apply vacuum to that small black hose. You can apply vacuum with your mouth if you have to, it doesn't take much.

If you get free flowing fuel you have eliminated the tank and petcock as a source of problems. If there is no or weak flow, you've probably got a blocked or faulty petcock.

 

My petcock and fuel strainer screen were bad because the previous owner let the gas turn to varnish. The petcock diaphragm was deteriorating and the slide was stuck in place. I found a rebuild kit online and replaced the internals after a lot of cleaning. Works great now. When you suck on the vacuum tube that runs from the petcock to carb #1 you should be able to hear some kind of noise from the petcock as the diaphragm opens and closes.

 

well heres an update...I have cleaned my carbs reset my pilot screws all to 2 and 3/4 turns out. I took out my air filter and cleaned it. I also changed the vacuum lines. Now te bike wont even start.

 

1st - You've got a bad/weak battery - to the point that after the first second or 2 of continuous cranking, you may not have enough juice to produce adequate spark.

2nd - do the testing - Fire/Fuel/Air - you gotta have all 3 to run. After that much cranking you should have wet plugs if fuel is being delivered. While you have the plugs out checking if they're wet, check for spark on all 4.

but first, you've gotta get a reliable battery to crank with - that one is toast.

 

Well I charged the battery right before I took that video so does that mean its a bad battery because i bought it like 3 weeks ago?

 

Voltage and Amperage my friend. Your battery may be able to hold a charge but its cranking amps that turns the motor over. If you don't have a volt meter, take the battery to the parts store to be tested.