right. ztrack said cams wouldn't help because of clearance. I don't understand. I thought racier cams just kept the valves open longer, and I guess I was asking if it's interference motor, and that the interference is so great that making hotter cams is next to near impossible?

But then, why couldn't you grind them down and flatter, to keep the valve open longer but not push it down so far?

I'm just trying to understand.

rock on, thanks for explaining!

Horsepower costs money how fast do you want to go. 

I wonder how much horse-power, a heavily modified 250 could put out? Aren't there some owners who club race these things?

40hp or so I'd say... then there is gas, turbo, etc...

Felix

It is this line of thought that makes me question a 250... all this for less than 10%?!?
All that to upgrade a already tiny motor? No doubt we all want maximum fun from our beloved between our legs... Love it for what it is or move on-

I would say for a 1000 dollars. I.E .full exhaust  Ignition and carbs plus a sprocket . The stock bike trans forms from a 25 hp Very Quiet 70 mpg great bike into a really fun machine capable of anything the street had to throw at it . After that LOTS of money is needed and the bike needs more than power. The first grand makes the bike peppy . Thrilling to wind out through the gears. Try winding a liter bike out through three gears. You will be in the next state.

But with more power comes some drawbacks. First this is a 3500 dollar motorcycle . The suspension holds the bike up . It Even handles well for everyday riding. But pushed the fork and shock are the first things to show there price tag.
Then the non radial tires and the frame flex all over . Not bad with 25 -35 hp . But with out 3000 dollars worth of suspension 2000 dollars worth of power stops being fun. and for 5000 you can get a 600 that weighs less has phenomenal brakes and an aluminum frame.
No one loves the 250 ninja more than me . I have had the bigger bikes. To get more than 35 hp the real money will need to be spent . even old 600s have 75 hp.
 But HP is not what it is about . This bike is about riding . Going places for 10 dollars worth of gas .about not paying 2500 dollars for insurance . The 250 ninja is a great bike doing a couple mods And is fun and that is what you are buying FUN.

Cams may come someday.  It really dose not cost that much to have you cams re ground .About 350 bucks if you need to contact Megacycle.

Hey a grand isn't much for a ninja sleeper heck you save that on ins in a year well worth a little monster