i just bought this 2003 450 sx i have read about them having bad welds on the stock valves or something like that. now its said that ktm backed there bikes and replaced the valves does anyone know if this true i talked to the origanal owner and he said he would call and see if it was done he just had valve work done because the bike sat for years due to injurys and will ktm still honer there word if it has not been done and if the original owner takes it in?

You'd be well advised to call your local KTM dealer.