Only runs smooth on reserve

[Joel]

Suddenly my bike is having trouble running with the petcock in the "on" position. I switch to reserve and it runs like normal. When in "on," it goes for a few minutes and then starts to sputter and pop and easily stall. I pulled off the gas tank and pulled off the petcock. Since it doesn't exactly pull apart, cleaned it with paint thinner and blasted some air through it. When I put it back together, same thing happened. Any ideas?

 

[Sandrew]

If it's not getting fuel in "on" position, then you seem to have a vacuum leak.

 

[HoughMade]

Agreed. Is the vacuum line hooked up and in good shape?

 

[Joel]

It's hooked up. I'll take a closer look at it in the morning.

 

[OliverB]

You may have to pull the fuel tap apart to get a look inside. Rebuild kits with new gaskets and diaphragm are easily available.

 

[Joel]

Thanks a lot. I found a worn spot near the end of the vacuum hose and snipped it off. I also noticed the cracks in my rubber carb boots are getting pretty deep so sealed them up with some glue and electrical tape. Everything works fine now, but I'm going to order some new carb boots.