Searched the threads, didn't really find anything that answered my question. The last few months I've had a loud off ticking noise. I've adjusted the valves 3 times in the last 6 months! I narrowed it down to the rear exhaust valve. Got it torn apart again so I can get to it. A .012 will go in snug but not over-tight. Do I want to tighten it up a little?? Do these bikes have lifters?? Bad one maybe? At my wits end! Bike runs strong, but the tick doesn't sound normal compared to the other valves. HELP!!