There was a racing version of that, I think maybe an nsr. If it's anything like the yamaha dt 250, there are restrictions built int the ports as an effort to detune the motor, The DT's have a notch cut to the depth of what the intake port would be, and from what I understand you remove to the depth of the notch and you have the original configuration before the detuning and you get 50% more hp. I'm not sure if it kills the low end, but I'm sure it's been done.
I watched one of those NSR's that was at a Scottsdale Harley shop, and it was there for years, had 74 miles or something like that , probably didn't run and they were asking 1100 for it.
I think those little bikes are as fun as any , and are about the cheapest way to get around and without making you look like a scooter jockey.