I´ve got a 1971 Honda XL 250 I´m working on. Guy has been trying to fix it for years with no success. It started and ran but only after bumpstarting it never on the kick. First thing I checked was the valve clearances which were way out so I got them in spec (0.5 inlet 0.8 outlet). After that it still wouldn´t kick start from cold but would when hot so an improvement. Next I checked the points and they were also out plus they are worn at an angle but I did my best to set then correctly. Then I adjusted the timing which was out slightly too, got it to fire up the multimeter as soon as the flywheel touches the F mark. This time when we bumpstarted it it ran for a few minutes, stalled and we haven´t been able to start it again. It smells very fuelly and the spark plug gets black very quickly, too rich. Any ideas what could need adjusting? The carb had been cleaned before I touched it but perhaps it needs adjusting now that the timing has changed?