I know your purists will take exception, but when I have a slow leak or even a total flat, I put a pressurized can of tire sealer in my road tire. It does the trick, and doesn't foul the valve. The sealant stays in the tube and helps prevent future flats. My LBS has cans of this stuff that will fit a Presta or a Schrader. A can costs about $9, but it's worth it if you don't have to change a tire 20 miles from home. The pressure can inflates the tube to around 80 pounds.
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"I am a true laborer. I earn that I eat, get that I wear, owe no man hate, envy no man's happiness, glad of other men's good, content with my harm." As You Like It, Act 3, Scene 2. Shakespeare.
"Deep down, I'm pretty superficial." Ava Gardner.