That's not really true. A law was passed decades ago that you or anyone you choose can do maintenance work on any machine and the warranty is still good as long as the job was done properly. Checking valve clearances is not a warranty issue. It's a maintenance issue. Long ago, people were forced to have maintenance done by the dealer they bought their machine from but that changed long long ago. Now, if you changed the valve shims incorrectly and it caused damage, that wouldn't be covered under warranty. Triumph cannot void your warranty of maintenance work done by you or a non-Triumph certified mechanic unless the work caused the problem that you wanted to claim under warranty. I wish I could remember the name of the law in question but you can find it easily with a search. So go ahead and do your own maintenance work if you like. Just do it right. Like many here, I do ALL my own work. And I trust my work more than I trust any mechanic's that I don't know personally. Since the 1960s when I got my first car and motorcycle, the only times jobs have been screwed up was when I got lazy and had someone else do the work. And I don't trust my Triumph service department. They don't seem to know what they are talking about - even about the most basic things.