Ok, so my 93 kat has been having some issues. Its been riding good but recently it would sputter, spit black smoke out exhaust, and crank but not start. I would hold throttle all the way open when i hit the starter and it would just sputter around 1500 rpms, then once i let go of throttle it would die. This problem would consisnt for a bit then out of no where the bike would run ok again. I put super in my tank, some told me that might be my problem and to switch to regular gasoline. Any advice?? Thanks so much.