Do timing chains stretch much? I put a 450 cam with autodecomp in my wr400. I was soo certain I had the timing correct and the valve shims correct. But after I ran the bike for a little while I could noticeably hear my valves clicking. I have a new timing chain I haven't installe yet. When I was setting the timing the marks seemd to be half a tooth off from TDC. I was thingking that if I installed the fresh timing chain it might help lining up the timing marks easier. Is changing the chain easy? Do you have to remove the flywheel? Does this flywheel require a flywheel puller? Sorry for the 20 questions.