Bike has been making alot of noise so I take her to the dealer and they say rear cyl. piston slap. Bought bike 2 years ago with 5,000 miles now have 30,000 and I have used only Redline syn 20/50 changing at 3-4 k miles. How could this happen? Is there something else could have caused this? It's a TC 88 EFI stage 1 air samson s/o and PCIII.