My bike called for 500 miles...not every 500, but after the first 500. When I opened it up, I found the valves were not well adjusted. I think it is a cost-cutting measure at the factory. They rough them in and count on the service dept to set them properly on the customer's dime. Of course, there is probably some wear as well... but the amount of error I found couldn't all be wear.
As for the ex500... did all of this happen right after you switched to reserve?
The way reserve works on those tanks is that there are two drain points, one at about the lowest point the manufacturer could manage, and the normal one an inch or so higher. If the previous owner always kept the tank full and never switched to reserve, stuff may have collected in the "reserve" part of the tank. It isn't a problem until you need the reserve... at which point that stuff gets sucked into the engine.
A lot of that "stuff" is water (which is heavier than gasoline)... it can be from condensation, it can be from the gas pump, or it can be rain or wash water leaking in.
It is a good idea to switch to reserve for 20 miles or so every time you fill the tank. That drains off the nasty stuff while there is only a little bit of it that the engine can pass without problem. Just remember to switch it back.
