I have a new star venture TC only with 1200 miles 2018 I took it to the dealer. I had a little knock on the engine. it's still under warranty. of the 5 years. They tell me that carbon in the valves. I had to adjust but that did not solve anything. then now they inform me that it may be the camshaft. that they are going to try to see that yamaha recognizes the repair. There should be consumer protection where someone has gone through this