Originally Posted by DaBlue1
If you feel you need more horsepower, ask yourself, what exactly do you want the bike to do and how much you want to spend? Sprocket changes take advantage of the HP that's on tap in the stock Ninja. Start there. If that is still not enough, look to spend anywhere from $350-$3000 on upgrades. Want to take off faster? Twist the throttle more. Keep in mind that the fastest, official record holding, & highly modified Ninja running regular gas still only goes 114+ mph in the States.
Because the Ninja is a little shy on the HP side, there's not a lot of power on tap to be had. The Ninja 250 is never going to be a powerful bike. The cost for the extra HP on the Ninja is pretty high for what you get.
Getting more HP, low end power or more top end, is going to be a trade off, meaning that if you want more HP, you lose low-end torque and HP to get there. If you want more low-end umph, you're going to lose top-end speed/HP. Also that great gas mileage you get goes out the window, when you start adding full exhaust, re-jetting and removing the airbox.
Some suggestions on mods for performance gains.
1-5bhp : Exhaust pipe, intake and jet kit.
3-8bhp : Porting, compression increase, cams, performance carbs.
20+bhp : Trade the Ninja 250 for a bigger bike.
Do the Jet Kit get the exhaust then learn to ride your Ninja like no other.
I weigh 250# way too heavy to be competitive on a 250 in the straights...yet i have no problems keeping up in the corners .
the Jet kit will make the bike more responsive
with gearing, more bottom end torque will reduce your top speed....