Thanks so much. I have been trying to find that valve timing video for 550EX motors for ages. The auto choke as you know runs from an inbuilt heat sensor on the exhaust, so if it's faulty it means replacing the whole exhaust @ $100 AUD. My choke linkage wire is badly bent and the sensor on the exhaust is also bent, which was probably done when I sent it into the repair shop to clean the carby a year or so ago. I may have to replace the choke wire linkage first. Anyway you've been a great help and I'll let the forum know how I go with the valve clearance settings.
