rd350

hi guys(please dont mind my english)
i recently bought a rd350f ypvs,85 .shipped it from amsterdam,holland to suriname(my country).it had been outdoors for almost 3 years before i bought it.
when i brought it home,i took the carbs out,also the tank cause everything was glogged.surprisingly after 3 kick the monster was running already.
i took it for a ride and i reached 140 km/h,this was the maximum speed which the former owner could get out of this engine.
my questions:
(1)when i reached 140 km/h the engine stopped running,can somebody tell my why it happened? i had to choke it to get it running again
(2)should this be the topspeed for an rd350 f ypvs?i was hoping 2 get something more than 140.
i am still working on the tuning so if anyone could tell what 2 do ,im looking for good acceleration and movement under the 100 km/h.
the ownersmanuel(book) is being posted to me at this moment.
hope to hear from u gyus
hes