My 02 softail wouldn't start easily - tech found a pile of tarry crap and brown gunk in bottom of float bowl. Caused needle to stick in jet making it too rich for easy start. This is after 3 years of using 98 high octane (Australian) gas and HD Duralt additive with every tank. I can only put it down to dirty fuel from gas stations. Has anyone had similar experience? Is there any way to clean crud out of the fuel system beyond draining the tank, or any additive to clean the system?