I just did a lot of maintenance stuff since it looked like the previous owner hadn't done it in awhile. I cleaned and lubed chain, changed oil and oil filter, new spark plugs, new air filter. Seemed to smooth out the engine overall, but the knocking noise is still there (no difference in it). I used 10w-40 oil specifically marked for motorcycles with wet clutches. The auto store I went to didn't have any 20w-50 for motorcycles. I do understand that I should probably use 20w-50 due to the warm climate but I wouldn't think that would cause the noise.