can you run high octane in your z 250 will you have to change any thing in the carb will it make a differance in the prefromance at all

 

No, its only good for high compression ratios to help with detonation. You won't notice a performance difference.

 

You can if you want.
NO, not unless your running an oxygen based race fuel. Then you will have to richen it up.
Mmmmmmm, depends. Again, if you run a high octane, oxygen race fuel; well yes, you will if you tune it right. Thats a hard question, but, yes, it will make more power if tuned right. If your talking about dumping in some octane booster and leaving everything stock, no you won't make more power, and could loose some.