Guys I think I have a crank seal problem. I already post this about a month ago that my bike sometimes idle at 1500 then sometime it goes up at 4 to 5 thousand RPM. But my question is how can I be sure that its a crank seal problem? Could it be blocked jets cause I dont have fuel filter and the last time I opened by carbs it full of dirt in the bottom. could a block jets cuase this? I want to be sure because oil seal are quite pricey plus the trouble of opening the crankcase. any suggestion? or how to be sure what the problem is?

Thank to all..