KX125 '98 tuning. big bore?/port timing? HELP!!

I am converting my mxer into an enduro machine, which is going fine but...
I feel the way the power kicks in the midrange is gonna catch me out on some of the more tricky stuff, and it's a bit low on torque. I want tuning options which will smooth the hit out and increase low end torque without losing any top end.
Would having the ports altered/polishd be enough? or...
I was considering a big bore conversion but what is maximum cc to still be legal in the 125 class? and how much reliability would it loose?
What do you think of flywheel weights? To me on a 125 it doesn't seem like the way to go.

FAO Eric Gorr

Would that be the front cover or the side one?

EricGorr please reply

I've not had much chance to ride the bike yet so I've not experienced this problem but what about modifications to the cylinder and/or cylinder head without a big bore, as the limit as you said is 125cc? I dont want to lose out on any top end (gain some if possible) but would like more torque.:think