I have a 1986 250R, with the motor bored .80, ct racing exhaust. I was looking into getting a bigger carb, and reed and valve change. I was not sure what size carb and jets I should get. Any suggestions??

The average summer temp here is about 50 degrees, and during the winter the average temp is around 25 degrees. I am at sea level.

I ride on trails, tundra, and beaches, and dirt roads.

 

I would say either a 38mm Air Striker, or a 39mm PWK. That will give you lots of room for future upgrades, and they are good carbs

 

ditto