I had a friend drop off his 03 Rincon for me to check out after someone told him his cam was bad. This unit has always had what sounded like valve clatter, but usually it quieted down after a minute or so. I also suspect that the owner put some cheap oil in it to get him by a couple months ago. I personally haven't heard of cam lobes wearing out before, but I'm not super familiar with the Rincon engine. I've always worked on dirt bikes and was wondering if the Rincon engine has any sort of internal compression release as the CRF450 does. I didn't see one, but I wasn't for sure. The reason is I pulled a compression test on this unit with two different gauges and they both show 65-70 psi. I know on normal four-strokes it's around 140 or so. I checked the valve lash (.006 In, .013 Ex), which was spot-on, then removed the rocker cover and visually inspected the push rods and guide buckets and cam lobes. Everything looked good and I didn't want to tear into any futher until I was sure that I had a low compression situation.