Hey, I bought a used 03' 400ex not to long ago and decided to take it out for a ride on a couple of trails. Well when I was just about done I started up the quad and moved it to the back of my truck and I started to hear this weird fast ticking sound coming from the head. I didn't hear this when I first started to ride throughout the day. I rode a good 2 hours of slow trail riding and some fast riding on some open gravel roads. Any ideas of what this problem could be? I checked the oil before I rode and it was past the middle of the dipstick but under the full mark. So oil should have been at a good level. It wasn't performing bad or anything, but just wanted to check up and see if this is regular or not? I read somewhere that this could mean that the valves need some adjusting, or something about the cam chain? Just a side note, my quad has a new cam that provides more top end, white bros e-series full exhaust, and a new rev box that lets the motor rev about 1,000rpm's more than the stock one did. That's the way I bought it, also it has around 20-30 hours of use from the other owner.