there is no need to remove the front fender... slot it or drill it.. or just buy a 85/86 250r front fender, they look much better and dont go down as far..
as for running for 30 seconds and dieing... check the tanks for rust, common problem, or clooged fuel filter, or partly clooged...
200cc 5 speed, air cooled, low tech dead nuts reliabable 4 stroke, exatly add gas and go rock the wheels off it all day long, BTW aboutt eh front fender i call bs.. iv owned 3 of them.. 2 85s and my white 84..alll had front fenders there whole lifes and none of them smoked .. well my 84 did but it way fuel,
dg hardchrome, or dg rcm rcm2 exhausts are great on them, cobra's are junk.. loud and no power, honda xr200 carb and cam are direct swaps and well worth the power..
powroll usedto make big bore kits for them, but havent forever, and now and then one comes up for sale... but not cheap... westcoast usedto make swinngers for them, but also dont any more... BUT ya really dont need a extended swinger on one