fueling problem any ideas?

Ok so I've had my bike for almost a year now and still havent figured out this one problem I have with it.

I can only get 60 miles before I have to fill up which equates to about a half a tank it gets normal gas milage and everything just ones it gets to half a tank it starves out and acts live its out of gas weather is on reserve or not. My fuel pump has been deleted and I thought that was the cause originally but it just doesn't make sense as it should gravity feed just fine. Also my petcock has obviously been tampered with because on is off and the blank spot on the bezel is on and off is reserve. Also when you turn the gas on gas will flow out slowly with out vacuum applied to the petcock with vacuum applied it flows faster. So I'm thinking the diaphram has a small whole in it. but it still flows fine. I have a universal filter on it and the line that goes to the carbs from the petcock is straight not pinched and flows down ward.

Any ideas would help as I want to take the bike on some longer trips and having to fill up ever 50-60 miles would suck. Also my reserve does nothing as in i could have it on on and run out and put it on reserve and still a no go

 

sounds like your gas cap is not venting like it should.. need to clean it.

 

That's along the lines of what I was thinking. Does it suck in air when you open it for a fill?

Also, might be worth draining your tank to see if there's any crud in it.. or in the filter. I lived in an area where the gas was very dirty, and they guy who sold me my first VFR warned me not to run it down past a quarter tank or so. I ran it down to E once, and I almost dropped the bike during a tight turn, when it started choking - right after I refilled the tank.

 

It's a great idea to fully drain your tank at least once a year and shake out/wash out whatever scum has lodged on the bottom.

 

As far as the venting thing goes my gas cap is broken because the guy i got it from didnt have the key and he broke the lock their for it doesnt lock down it just kinda sits there so I know its not a venting problem. I'm going to drain the tank tonight and see if the flow changes as it gets lower in the tank. Also whats a good way to clean out the inside of the tank?

 

No pump. ok, so try this : put the fuel line (from the tank) directly in a bucket when you have half-tank fuel, put the petcock in position on and observe the flow. Of course without ignition !!! If the flow is normal then there is a problem of carbs. On the contrary, if the fuel flows stops there is a problem of air in your tank/fuel line.
Hope this will help.
Regards,
Carmine