Wimpy on anything over half throttle...

[goat81can]

So I have run into a bit of a problem with my 09 Kfx 450r. When ever I go past half throttle, at medium RPMs, the engine bogs way down. This problem happens mainly in colder weather. I always let it warm up to operating temps, before I get on and start riding. I have cleaned the air filter, and changed out the gas. I have taken it to the dealer and they found no problems with it, besides a slightly fouled spark plug(which they replaced). I chocked it up to leaving the "choke" on to long, but even after this the problem still remains.

I do ride at very high altitudes, 9 to 10 thousand feet above sea level. I realize that this is a fuel injected machine, and thus should compensate for the change in altitude. But I was just wondering if perhaps because of the very high altitude if it was a little far out for the stock specs? When I pulled off the air box cover I could feel an improvement in the performance, which made me think that perhaps it was just starved for air in the thin atmosphere.

Anyway any advice would be a huge help...oh and its a stock machine..

[ononewheel]

Ya the stock intake and filter is a joke!maybe think about getting an fci intake and maybe a efi controller and if possible a dyne tune!

[goat81can]

Yeah i was thinking along those same lines. Though I took it back into the dealer today, since its still under warranty. So we will see if they can come up with something.

[Slade11]

Goat please let me know what the dealer says. I have a 2008 model and it is doing the exacting same thing. I have tried all the things you have and still no luck. I am reluctant to take my in because of the cost and would rather fix the problem myself. Thanks for the help!