I'm just going to add that a person should do some basic observations themselves first. I'd say at a bare minimum is to describe the bike's setup, stock engine, intake & exhaust or otherwise. Also you should pull your spark plugs and take a look at them. There's a big difference between plugs that are wet and oily and ones that are dry and burnt. Have you checked anything yourself, and if so, what? Ever checked your valves or timing chain tension? Does it have oil in it?
The more you list, the better your responses will be.