My oil problem

So I had around 2000 miles on the bike and decided to swich to full synthetic. The only motorcycle oil (4t) I saw at the time was
20w-50. So I bought that at 10.50 per quart. changed the oil and filter, started up the bike and it ran like crap. Its was knocking and pinging like crazy. I let it idle for a few minutes and it got a little better so I took it out for a few miles. It knocked the whole time. It did settle down after 30 or so miles but every time I let it cool it knocked again every time I started it back up. Long story short I went back and got some regular 10w-40 4t oil, changed it again and it ran like a dream. I think maybe the engine wasnt broke in enough for the full synthetic oil. or maybe 20w-50 was just to heavy of an oil. Either way I'm gonna stick with regular stuff for now.