opinions?

[400exfan19]

i have a 2003 KFX 400 and find that when i am in the dunes, first gear is not enough for climbing the big hills and 2nd is to much and starts to bog. i need a sprocket that will fix that, any1 know what to do?

[wilkin250r]

I don't know the stock gearing on a KFX, but as a general rule, you'll only be able to change 1 tooth (up or down) on the stock chain length.

But that 1 tooth can be either front or rear. Changing a tooth in the front will have a MUCH bigger impact than a change in the rear. Plus, the front sprockets are generally cheaper.

[400exfan19]

any1 know the stock KFX front sprocket size? i believe it is 15

[Big - D Racing]

stock for a 400ex is 15 38 and for the dunes I run 14-37. Down in the front adds more bottom and down in the rear adds more top. Going down one in the front was too much bottom for me so I also dropped a tooth in the rear.

[xtullyx16]

u sure ur jettings right?? i dont think it should bug when ur climbing a hill in second unless ur dont have enough power! which a sprocket would help.. probably be as expensive as a slip on right?

[pro-rider46]

gear the front up 1

[400exfan19]

if i put it up 1 it would make it even worse........

[wilkin250r]

Originally posted by 400exfan19
if i put it up 1 it would make it even worse........

Not necessarily.

The problem that you have described is that 1st gear isn't tall enough, but 2nd gear is too tall and the engine bogs. You are stuck in a mode of thinking that you need to make 2nd gear shorter to allow you to climb those hills.

But think it through, couldn't you also make 1st gear taller? A larger front would certainly do that.

That may or may not be the best option, but it definitely is an option.