Couple days ago my 79 xs650 with aftermarket dual exhaust and pod filters started running a little off at highway speed everything else is ok . I thought my carbs just needed to be resynced . So i hooked up a vacume gage to my carbs and according to 2 it at lik 3 n 4 grand ish eg 70mph. cuz i got rid of my old tach and i am useing a tc bros overdrive sprocket the vacume gage reads late valve timeing . Now normally thats not a problem but my left cylinder plug when i try to remove moves about half a turn n then gets really really tight n hard to turn im afraid of stripping the plug hole n the jug .any thoughts on the plug problum aand im thinking a good re time should fix my late valve problem . I just wanted to conferm a couple things n get sum inputs from the rest of the xs comunity thanks .