Soooo... where do I start.
Changed the spark plug, so I had to remove seat and tank.  No problem, fairly easy, nothing special.  Fuel hose disconnect and vacuum line disconnect for the petcock, electric disconnect and tach disconnect and voila, the tank pops off.
Old plug out, new spark plug in, put tank back on, connect all connectors, speedo cable, fuel and vacuum line, put seat back on and vroom.. bike starts up like a charm.  Purrs like a kitten.  Sweet.

Test ride goes good for about 3 miles when all of a sudden the exhaust starts popping just the same way when I run out of fuel and have to switch the petcock over to reserve.  More popping and poof, engine shuts off.  

Try to start it back up to no avail, switch the petcock over to prime, wait a bit and vrooom... bike starts back up.  
Switch petcock back to On and continue my marry way.  Another 1 or 2 miles and pop, pop, pop, poof.. engine shuts down again.  

So, now I switch the petcock over to prime and leave it there and ride home.

Petcock back in On position I remove the fuel line from the carb, remove the vacuum line, suck on the vacuum line and fuel starts to flow out of the fuel line.  Uhh... what the heck?  Ok.. put everything back together, petcock into prime position, start the bike, petcock back in on position, another test ride, same result.  Carb runs out of fuel and bike dies.
This time I only remove the fuel line, start up the bike, and watch fuel flowing from the fuel line in a nice stream.  At that point, I'm completely stumped.  So I have fuel flow whenever there is a vacuum on the vacuum line, but the bike dies in that position and runs only well in prime position.  WTF is wrong with it?  At that point, I'm almost inclined to just switch the petcock to prime everytime I want to ride, but it's eating me up as I like to have my stuff function the way it's supposed to function.


Anyone else experienced such a problem before?  I really don't know what to do anymore besides switching out the petcock or just switch to prime position without having the reserve switch when i need it.

Thomas

You might want to check the vacuum port on the carburetor and make sure it's clear into the throat of the carb.  You might have stuffed something into the nipple when you put the vac line back on.  A small piece of wire will work.  Disconnect the vac line from the petcock and blow into the carb.  The Raptor petcock fix is simple, two screws in and out and plug the vacuum nipple.

Probably not the cause since it's running on prime but I'd check the screen on top of the petcock.  Same thing if you have an inline filter, replace it.  If the vacuum line is in good shape and sealed tightly at both ends with clips the problem has to be in the petcock.  Doesn't sound like anything you've done could have caused the problem but stranger things have happened.

You don't have any signs of gas when you disconnect the vacuum line at the carburetor do you?

How to check your petcock,... ...

No, I haven't checked the screen yet.  I guess that's next.