I built a generator like that that I still use. My first build had the Honda GX140 5HP motor and a 12 Volt Delcotron 63 amp alternator next to each other with a belt. This combination ran the alternator backwards, and it overheated. Next, I bought the direct drive brackets and the Lovejoy couplings, from The Epicenter.com. I had to replace the rubber cross once, because it wasn't straight and it wore out. Since then, I keep a spare on the shelf, because two are cheaper than the fuel to get one. With one on the shelf, I haven't had to replace it for two years. It is used for about 4 hours a day, a couple of days a week. I made no alterations to the alternator, other than replacing the pulley with a coupling half.
Rod.