Can you help out a total beginner? We are running an '05 450R in a race at 1200 elevation in temps about 80 degrees. At home we're at 3500 elevation and it's hard to get the setup right. Stock carb. Planning to run a mix of 50/50 race fuel and 91 octane...When we run the stock 170 jet it seems to run OK in the mid range but we have trouble on the high end. Which jet size should we try? Thanks!