Never could get that F7 running right. I think it needed new crank seals. I cleaned about 15 lbs of goo out of the exhaust, rebuilt the carb with all new parts, rebuilt the auto-lube pump, and it would start, rev in neutral no problems, run down the street, and then bog and die and not make it back up the street or restart. Plug was wet with oil - a new plug and it'd start right up again and do the same thing. I ended up selling it for next to nothing. PO said he had the ports opened up and fitted a larger piston, and either he effed it up or it needed new crank seals or something else was wrong. I had too many bikes to stuff into a 1-car garage at that time so I let it go for $300 or so.
Charles.