Might Vac's kinda don't suck enough. Might try installing some speed bleeder valves to help you. They keep air from getting in by using a small one way valve. They're cheap and work well. Here's a picture of one so you can see how it works: http://images.google.com/imgres?imgurl=http://www.raceshopper.com/images/speed_bleeder2.gif&imgrefurl=http://www.raceshopper.com/speed_bleeders.shtml&usg=__hw35lbEY6mgNnnwMYcw1hHyJFi4=&h=320&w=460&sz=20&hl=en&start=1&sig2=O-gBZeESNaeJ3JvOwLWtdg&um=1&tbnid=cFDYmbMspIy-aM:&tbnh=89&tbnw=128&ei=tXY6ScqEF536NPX-nLoF&prev=/images%3Fq%3Dspeed%2Bbleeder%26um%3D1%26hl%3Den%26rls%3DHPIA,HPIA:2006-09,HPIA:en%26sa%3DN These will set you back around $12 each and are available through any bike shop via Tucker Rocky - Parts Unlimited, etc. If you have access to compressed air, get a bleeder like this one: http://www.sandhillspowersports.com/sandhills/OnlineStore.do?DSP=200&PCR=1:70000:70034&IID=sbs_bsbacc_06 Beats the shit out of a Mighty Vac and will bleed lines in about 2 minutes. I have this exact model and it works well. Snap-On and others make one just like it. They run about $200. Price on this webpage is obviously wrong - must be on sale for $175.00. When bleeding lines, the air is usually trapped at 90 degree bends - such as where the banjo bolts attach to the master cylinder. Mighty Vac often don't have the pressure to clear these areas. Tapping the 90 bends lightly with a screwdriver handle or some hard plastic will sometimes help jar the air bubble loose. Or use a power bleeder and be done with it ina minute. And if you're just changing fluid, don't drain the lines - just keep adding new fluid as you suck out the old and the fluid drained becomes clear. It's much harder to fill and bleed an empty line than it is to run fluid through it. You use a bit more fluid this way, but it is much easier. Good luck!