If you want more passing power on the freeway 13 tooth is great, going about 65mph your 6th gear is in the sweet spot, one good full throttle pull and you are up to 85 in no time without downshifting

 

So I won't lose any top end speed? I do mostly street riding with some trail riding. Just looking for a little more power. thanks

 

You will lose top end speed with a 13t counter sprocket, but you'll gain more torque. If you do mainly street I'd stick with your stock 14 or go up to a 15. I max out at 80 mph (actual) based on my mods with a 15t.

 

Why don't u just try it. It's cheap for all u know u might like it . I have no problem going 65 with my 14/49 but I ride trails 99%

 

Brieninsac, do you lose much torque by going to the 15? Will the new pipe compensate the loss if I go to the 15?

 

Klx250sf 13/39 = 13/42 (due to tire size differences) top speed 95 mph, actual, probably around 80

 

Get a 13 and 15 tooth front sprocket. Cheap and you will have all the bases covered.

 

My powercore4 was pretty noisy new not awful but not quiet. I didn't feel the powerbomb (header) affected my jetting at all. Like I said I did the slip-on first without the jets and the bike was fine I didn't check the afr at that point but it was good to go. When I opened up the intake side was when I jetted it, as you could tell it was lean with just the lid off at that point. My bike is an 09 with about 6K hard miles on it and it still runs like new (only better).

 

For the type of riding I do a 15t is fine. I have no problem popping the front if I want to. Where I notice it is at max speed into a head wind. The bike will only do so much.

 

do i need to do anything to the chain if i go to a 13 or 15?