The stock float needle was a metal to metal type. There is a viton rubber one available that works much better. There are also some set up tips on this forum.
If the issue is just when the bike is cold, you could go to an oil with a lower first number possibly a 5W50 or if where you live it never gets very hot perhaps a 5w40
Sometimes people lose the needle jet when cleaning the carb. Some bikes run poor to fair in this condition but will not run great.If you take the airbox off at the carb, there should be a brass coloured bit sticking up from the bottom of the carb. That part is the needle jet. Good luck.
The first generation Pampera (released approx 1996) had a smaller radiator than the later models. These first Pamperas also had the "trials gearbox" , later models had some gears with different ratios.
