Hallo! Finally got my 550 running properly, at least for a while... My problem is that left cylinder does work only every now and then. Carbs are rebuilt with "free flowing" aircleaners (with 110 mains, maybe those are too big? for mild porting, little higher comp. + "race" chambers), ignition is new newtronics (breakerless). When engine is running on idle, the left cyl. seems to do ok, but when I take her for a ride, it will only take `bout 5 miles of driving when I can feel the engine starting to "surrender", I mean power drops somewhat. When I stop the bike and try pipes, the centre & left pipes are warm (hot...) and the left one is significantly cooler. Any suggestions where to start troubleshooting. I have tried NGK plugs from heatrange 7 to 9, doesn`t seem to make any difference...And by the way, how big gap would you set to plugs and what ignition timing should I try?