Hi,
at what milage do you guys change you primary chain ?

There isn't a laid down interval for primary chain replacement...

How quickly the chain wears will depend on how you ride, the quality of the chain and how well you maintain the chain. For example do you keep it correctly tensioned and do you check and maintain the primary chain case oil level frequently to ensure it is well lubricated?....

There really are too many variables to be specific...

If you've run out of adjustment then it's probably time for a new one.. , but on a more serious note, check out how to assess the wear in a motorcycle chain on the internet or in one of the older motorcycle maintenance books...Ian

email (option): ian@wright52.plus.com