When I thought I was immortal I had an old Yamaha 125 Enduro that I had to just take apart and put back together every couple of months to keep it running. It was something electrical with the magneto or something, never did figure it out.
After I broke my leg on my YZ250 I realized I was not immortal, sold all my bikes, and decided if I was going off-road it would be with 4 wheels and a cab or roll cage of some sort. Was instrumental in getting the signs put up prohibiting 4x4s on the bike trails