Hey all - I bought an 84 XR500R. Brand new to working on these. Kinda beat up but I want to try to get it going. Tore the engine down. Cam tension guide was broken so chain was loose. Cam moved a little to the left of engine and one of the cam bearings made it´s way off the saddle. No major damage that I can see as didn´t run long like this. Micro fiche shows dowel pins on outside of both bearings however none exist in the head. What keeps the bearings in place? Seems to me they could move over time or you could bump them during assembly and move them outward without knowing.