hi, just got a rmz250. havent ridden it yet. the jetting was out when i bought it. it would start 3rd kick would idle and run fine but after that when u try it a big rev theres like a flat spot. its not bogging, just a flat spot. the muffler core was snapped in half so i think that might of been part of the problem. since then i have put a full dr-d exhaust system on. i started it but didnt rev it because it was late at night. i was told to go 1 size down from the stock main jet ? whats the stock size ? im in victoria, australia. have no idea on my elevation level. the reason the jetting was out is because he didnt have the tool to adjust it. pic.