Hello, I've spent the last hour reading and searching the forum about normal and abnormal engine sounds as well as valve clearance checking for my '99 WR400 (which I've owned for a month now). Two weeks ago I noticed occasionally at 5,000 RPM (I have a Trail Tech tach..) there would be a relatively high pitched clicking that would sound randomly. (for those without a tach: around 40 mph with stock gearing in 5th gear). I know what valve knock sounds like in a car, but the WR has no rockers, so I don't know what valve lash sounds like. The sound on my bike is almost exactly like if you take two deep sockets (for a socket wrench) and hit them together (strange analogy, but it's true!!). Okay, now do that at 2,000 times/sec. j/k. I kept on riding the bike (on the street primarily) and about a week later, or 150 miles, the sound is there ALWAYS at 5K, but now also from 4K to 6K and is loud. And it doesn't make the sound unles the engine is under a load (by revving in neutral). The bike has been performing normally (starts, idles, power, all fine). I just checked the valve clearance and they are all in spec. I used those wide feeler gauges for cars, but they fit and I made sure that they were parallel to the valve bucket/cap. So hopefully I got correct numbers. Soooo.. I guess I'm just wondering if, based on the sounds I described, my valves are actually out of spec or there is something else I should check (flywheel key, clutch basket, etc..). I just thought it was the valves for sure because the sound was sensitive to engine RPM (something internal that was oscillating, not rotating..). Please help, I can barely go a day without riding it. . THANK YOU!!!!!!!!!!!!!!!!!!! Sorry for writing so much .