I think this is the problem. But i dont think its the whole exhaust that is changed. Its atleast a Cobra pipe, but i dont know if the rest is stock? If i provide a picture of it, will some of you be able to identify it?

I really dont think the previous owner changed the jets. when the summer gets here ill think i just get a shop to install jet kit and a filter and set the carbs up corretly (if i can get it to start by the summer xD )

 

hey man i had the same problem and i couldent figure out what it was for the longest time, i just ended up pulling my carbs draining the bowls and cleaning them. also chances are your plugs are F'd from all that cranking so if ya get a chance to pull them it would probably be a good idea.

 

If you just have the aftermarket can and stock header/air filter you should not need to re-jet. Yes, if you post a picture I am sure someone will know what kind of exhaust system it is. Obviously a re-jetting would be a good idea if you think the bike is running lean but that is probably not the cause of your starting issue. I would go with new plugs and a proper carb cleaning (at least semi disassemble and spray through with compressed air).