screens in gas lines? or blocking of cocks?

[HomeNuget]

I posted before about the correct possition of the gas chicken. It is in the correct position, yet bike bucks a bit at faster speeds, thus tellin me there are clogged screens, or has anyone had any issues with the cocks clogging? Is there a screen in the Tank Itself?

Just a note

There is no rust in the tank.

[Kerry]

1) There IS a screen in the tank itself.  See:
View from inside the tank
and
Removed from the tank
and
BikeBandit "Fuel chicken" entry for a '99

2) There are no other screens or filters in the OEM fuel system.

3) The ON and RES settings on the frame-mounted petcock function by vacuum pressure, when the bike is running.  You may have a problem with the vacuum-actuated diaphragm in the petcock when using the ON & RES settings.  Also, check the vacuum line (and connections) from the left carb to the petcock for leaks.

4) The PRI setting works by gravity only, whether the engine is running or not.  Try running on PRI and see if that makes a difference.  If the symptom disappears then the baseline flow from the fuel tank is OK, but the vacuum "circuit" is probably faulty (see item 3 above).

5) If nothing seems to help, you can always block up the shorter (ON) outlet from the fuel tank petcock and run a line directly from the longer (RES) outlet to the lower T-connection between the carbs.  If you prefer having at least an ON/OFF valve in the system, consider a (pricey) Pingel valve, a generic motorcycle replacement valve, or a  cheapo riding lawnmower unit from your local home center.

EDIT: Changed links from sisna.com to bbburma.net