89 gixxer's fuel supply problem, advice?

[Beak]

I have an '89 Suzuki GSX-R250r, and I've twice now managed to run the fuel line dry... It happens when I'm going near top speed (from 165-190km/h) for a little while. As soon as I drop the revs slightly, I lose power and slow down, exactly as you'd suspect a bike running low on gas to do. This happened just recently on a ride out to the Nelson lakes, and it kinda ruined the trip a bit when we wasted 45 minutes trying to get her to go again...

I also own a crashed, but mechanically sound '89 Yamaha FZR250r. This bike has a fuel pump, but no registration. I wouldn't have a clue if the gixxer has a fuel pump, but if it does it's probably broken. I want to install the FZR's pump in the gixxer, but being a newbie, I have no idea how I should uninstall or install it, or even if I should. I'm planning on giving my gixxer a bit of tlc over the coming weeks (new chain, sprockets, oil change, fix a bunch of cosmetic and wing mirror problems and possibly clear out my carburettors, money willing), so does anyone know of another reason my bike could be acting this way, and whether I could fix it while it's at the mechanics without pulling apart my FZR?

(also mods, I have no idea where exactly to put this thread, feel free to push it wherever)

Cheers

[Madness]

Try checking for blocked fuel lines and/or filter first. Then slow down, Rossi.

[nadroj]

Your fuel supply problem could be a blocked fuel tank vent causing vacuum in the tank or a partially blocked filter inside the tank on the back of the fuel tap / outlet.

[FJRider]

Your fuel supply problem could be a blocked fuel tank vent causing vacuum in the tank or a partially blocked filter inside the tank on the back of the fuel tap / outlet.

Or the vacuum hose/valve needs attention.

[MSTRS:Me]

Your GSXR is drinking fuel from the bowls quicker than the tank can replenish it.
It is a simple gravity feed system - no pump - so you do, indeed, have a blockage somewhere.
Could be the vacuum hose from the manifold to the petcock is not operating properly. Try doing a run with the tap set to Prime. If this fixes the problem, then fit a new hose.
Could be sludge buildup in the tap or inlet tube/s inside the tank. Remove tap and thoroughly clean all of it. And flush out the tank too.
Could be a blocked breather tube, causing a vacuum buildup in the tank. If air can't get in to replace the volume of fuel used, then the fuel stops leaving the tank. Try a run with the fuelcap partly open.
If the fuel hose has an inline filter, that could be at the end of it's life and/or has the wrong flow rate. Replace it.

My guess is sludge in the tap.