I have a 05 YFZ450 and the problem i am having is bogging at low rpm's and right around mid range the motor likes to hickup or say load up with either too much air or not enough fuel, once im past that point im either smoking the tires or getting thrown off. I have just some simple mods, Dynojet Jetting kit , Exhaust cam advanced 1 tooth , SRP Cdi Box , K&N filter (no lid) and 1 tooth up on the front sproket. I run nothing less then 93 octane and live in NY. My Aim Name is Tha3rdman1 im hoping to find some help here.

thanks ahead of time
~Brian

 

sounds like you need the aftermarket high flow accelerator pump cover......i think boysen makes it for around $60

 

Personally, I'd get rid of the Dyno jet kit and use factory jets and needles.....
I hear a LOT of problems with people and their jetting after they install one of those kits...

Your problem is probably the needle setting at those RPMs. Try going up and or down on the needle to see if that helps.

I have an 04' and am using the stock needle on the 5th clip position, 172 main jet, 45 pilot, and the fuel screw turned out approx 2 1/2 to 3 turns out. Runs like a champ from bottom to top.

Might give that a try too. [img]i/expressions/face-icon-small-smile.gif[/img]