Motorcycle Repair: tapping noise from top end, yamaha virago 750, kawasaki kz

Question
Hey Wayne,
         I have a '82 Yamaha Virago 750 which has a tapping/ticking noise coming from the right side petcock.
With engine running I opened the gas cap and put my ear towards the inside of tank and when I turn the petcock from 'on' to 'reserve' it changes the sound of the ticking. These petcocks are vaccum operated. What could be the problem here? Could it be something wrong with the petcock itself or a problem with the vaccum operated carb on that side.The other petcock does not have this problem. The bike runs good except for a mild backfiring upon deceleration. If you think it is the petcock, can it be pulled apart and cleaned up? Thanks for your help!

Answer
Gary,


Do you have a fuel pump?
-It only pumps when it senses
the need, so it may click a few times when you first
turn on the key and also when the bike
is running of course.

Mild backfiring is fairly normal,
Richening the idle mixture screws slightly may help and
make sure no exhaust gaskets or joints are leaking.

If you think it's the petcock clicking
fuel petcocks can be rebuilt if necessary, but find a rebuild kit
supplier first. I believe there are some online.
Often Kawasaki KZ models petcock rubbers will work too.

You can try cleaning the petcock,
maybe something got stuck inside it.

If a petcock fails it may suck fuel
into the engine and foul the plugs.