Motorcycle Repair: 1994 300EX oil, honda 300ex, stock tires

Question
I have just bought a 1994 Honda 300EX, but I am not sure what type of 4-stroke oil to put in it (i.e. 10W40, 10W30 , etc.)- I couldn't find this anywhere.
Also if i were to rebuild this engine what are some key things i need to fix, replace, or clean to get it running in great shape.  
What size rear tires do you recommend because when i bought it, it had 20x10-9 but after researching i found that stock tires are 22x10-9.
Thanks for all the help.

Answer
Hello patrick,

And the oil question is different in everyones eye's. I run 10/40 Bel-ray in all my bike's. But im sure someone will dis-agree with this. And two, you have the most reliable bike there is there the motor alone. Tire size is up to you, smaller are i should say short the bike tire fast take off taller the tire the faster you will go. It kind of works like that.