Hi guys. My bike has done only about 25k in 5 years. I recently had an intake & exhaust valve change on my mechanics suggestion, as there was a complete loss of compression. Change of valves fixed that issue. Now 2 months later, I notice that there are white fumes coming out of my exhaust, which is discernible after the engine has warmed up a bit. I suspect it to be engine oil getting in the combustion chamber. I noticed the spark plug electrode had black carbon fouling, a little wet to touch. I have replaced it since. I also checked the inside of the exhaust pipe, in the morning, with my finger, it was dry, powdery carbon deposition. I need your help guys, what do you think is the reason? How should I go about the detection and repair? Could it be that the valve replacement job was faulty and it is letting in the engine oil? Or the problem is far more serious, piston and engine block related? My mileage has gone down to 30 from 42-45. No noticeable engine sound change, and the engine also doesn't feel like it is getting hotter than usual. I am an easy rider and I don't speed.