I just got one of these myself.... has pleanty of power for the tracks i am using it on. (Timezone Raceway,WA & Rose City, OR)
I did have to move the Nozzel IN (about 1 hour) to get it to run a little leaner. It was supper fat on the bottom, but ran hot on top.. moving the nozzel helped alot.
Mike Ellis has been a great help with tunning motors, so credit goes to him.
I would not mess with the port timing on it.. we looked at it an it looked really well machined and had nice craftmanship. I have the CRF version.. so far so good.