I have the same problem. Do to doing many long trips like to Alaska and back which was over a 10,000 mile trip and the terrain I went through on this trip and may like it the problem is getting the engine black really clean. I never washed my bike on a rode trip till the trip to Alaska and it got so bad I had to wash it off 4 times. You would have thought I was riding a motocross bike. LOL I tried S 100 but a few days after I put it on it looks just like it did before. I got some pig spit and one day going to try it but the people that make the pig spit said you have to make sure the surface is really clean and I cannot get all the dirt and stains off mine. The picture I posted shows what I am dealing with and was taken shortly after washing it.
Have a 17 year old fat boy, factory black motor, paint is strarting flake & peel off,anybody try auto engine paint like VHT or duplicolor,suggestions/tips Thanks all