I have been having some problems with my used 2011 YZ450F dirt bike. I checked the valved gap and one was out of spec so I took the cams out and noticed that the intake camshaft is stock but the exhaust camshaft has a Web Cam marking with Grind number 943. According to Web Cams website this is a very agressive grind. Can anyone think of why someone would have just changed the exhaust cam only? And why with a Stage 4?