i would say the biggest rod killer is cold temp run in. The rod cops a beating when its new, tight and cold run in rich. If you can immagine a sleeve tapered at the top and a piston non tapered. if the sleeve dosent get to expand through heat then the piston smashes into the taper. This shock then gets transferred to the rod bushing, crank pin and bearings.. Both on and off road engines punish the rod / pin relationship , there is a lot of free revving in off road , with less resistance it can really speed up wear. Im amazed that engines las as long as they do...