Might have something to do with running 927 castor oil Dez. I run the full synthetic and my bike barely smokes and doesn't spit much residue out if any at all at 25:1. Big difference though is exhaust smell, my exhaust smells like race gas with a slight hint of oil where my cousins banshee running a castor oil wreaks of two stroke oil/fuel mix and he mixes 40:1 I think.