I just purchased a 1980 CX 500 with 4800 miles on it. The bike looks like new and has been well maintained. It is making a very loud tapping/knocking noise that seems louder on the right side. I went thru the valve adjustment and re-adjusted each rocker arm. The only ones that were really of were the exhaust rockers on the right side. I was sure that I had found the problem but it didn't make sense that they were the only ones that were far off. I put it back together and it still has the same noise. I'm hoping it's not a rod or crank bearing. Could it be the cam is badly worn or the chain tensioner worn. This bike really looks great and it's hard to believe that it has any engine problems, but the noise is way too loud to be normal. Has anyone had this problem with a CX 500 with under 5000 miles?