Well in order to get the numbers your talking about, you will need to remove the engine, and replace it with something else. maybe a 600 or something like that.

Honestly, your not going to get 100 HP out of a 250. Just isn't going to happen, no way, no how. Not even with a RS250 engine thrown in there.

Your looking at 75 max on a NSR engine, and you won't like it, as it won't be reliable. Drop an RS250 engine in there, and now you can get 85 if your a good tuner. Still will be doing top ends more often, and doing a crank at least every season, if not more.

Of course if you just start out with an RS250 (Honda that is), then you will already have a bike that will out perform most 600's on the track.
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Charles Gallant