Hi all! I just found this website and it seems to give some good information. I bought my 81 KZ550 LTD a few months ago and it seemed to run good (yes it has some leaks but it is older). I have been riding it and enjoying every minute of it until this week when it started to backfire and hesitate. I believed it was a vaccum leak, so I check the tubes and no hole. In the process I checked the caps of the Carb and the screws were loose. I took them off and re-sealed them with sealant and gaskets. I figured that was causing my vaccum leak. I just tried it after completing this and it has lost some of the hesitation but not all of it. Does anyone have any ideas for me? Thanks in advance for an help you can provide.