I have a 2003 Honda CRF450 and I have had it in the shop to many times and the people never fix the problem. What is happening is when I am riding the bike it will bogg out when i twist the throttle just a little bit fast not even snapping the throttle. This makes the bike shut off at low speeds or when I am trying to climb a hill it will bogg out. I have only been able to compete in one race this whole season which has really disappointed me. I think it is due to jetting because i have had my valves checked at least 5 times in the past 2 months and they say it is fine. Z&M cycles says with my Big Gun full exhaust I should still be running stck jetting I do not know if this is correct or not. I submitted a question to big gun exhausts and they told me to run a 178 over a stock 170 main jet. but I think the problem is that the bike is running to rich. If anyone has any suggestions they would be greatly appreciated.