I have a 2000 Triumph Thunderbird with low miles. The last time I ran it was in Jan 2010. I turned fuel switch to on and fuel started running out. I turned off and stream stopped. I turned it on again the fuel is not running out? I looked at the hose and it looks like there are no defects? Should I attempt to start once the fuel has evaporated?

I assume that this bike is carburetted. Most likely the float needle in the carburetor, (or carburetors if equipped with more than one carb), stuck when you first turned on the gas. If the gas has stopped flowing when you open the petcock, you should be OK to start it. If the problem persists, you will probably have to pull down and clean out the carb(s). Pay special attention to the needle and seat. Make sure the needle has no corrosion present, You can use Scotch-bright to clean needle and seat.