It's not a "pinging" sound. It's more of a thump sound when I rev it in hot temperature weather, 80 degrees and up. I use 93 octane and also use the recommended victory oil. It runs beautifully in cooler weather up to 60 degrees without the strange sound. It also happened on the first warm weather, without any engine modifications (complete stock). Is this normal on these bikes? Now I have the new stage 1 exhaust with EFI calibration, it's still makes that strange sound when I rev in hot weather conditions.
2013 Cross Country Tour:D