The temp sensor goes into the return line, the one that goes out of the cylinder head to the radiator. Use the magnet bolt, it works good and just dig into the harness under the tank, let the bike idles and take a voltmeter, search for a 8-12V supply when the bike idles, ground one wire. This Vapor is easy to install the power to, it works from 0.1-300V I think. You can tap 12 V from the regulator as well.