Not sure how well you guys can help in this vague thing. Bike: DR650, The bike is new to me (few weeks or a month now), well kept and runs like champ. Has big tank and after market petcock (non-vacuum line and has off position). Stock carb. Few weeks ago bike the bike ran out of fuel while the petcock was set to "ON", I pulled over switched to "res" and cranked. No life, waited and cranked. Tried this over and over with no help. I pushed the bike to station. Filled it, waited and cursed my luck. And when I tried again I got instant life. Rest of that trip I kept it full enough to not touch reserves. Yesterday I wanted to purposefully try it again, run tank out of main capacity, switch to reserve and run that dry (spare in pannier). Bike stuttered when it ran out of main, switched to Res, all good. Then it ran out of reserve, full death, no stuttering.. I poured my 3 pint spare in the tank. No life. At all. Waited and waited, trying to crank every now and then. One point got to idle for a few sec but wouldn't run. choke made no difference. Eventually braining from the past incident I figured that the added pressure of full fill-up solved the issue. So I blew into the gas tank - tried and instant fire. Running all good like nothing happened. Sticky float needle? Would seem that it would rather stick open than close? Amy ideas? I removed the hose from the fuel tap and that was running freely. Has big tank and after market petcock (non-vacuum).