flat powerband

thanks but are they all like that stock they just dont make any real power can you get them to hit like my kx125 ive about 1000euro to burn coz my best mate has a 2000 stock trx400ex and its hard to keep up on the straght i really want to piss him off i dont want to get a bigger quad coz i love my blaster its light and turns very well better than that trx
 
well if you have 1000 euros to blow. its should go down like this F7 exhaust, open the air box lid, buy a 240 big bore kit either vitos or LA sleeve, then send that new top end to one of the technicians on this site to have it ported (before you do that decide if you want a stroker this will give more power more displacement and more throttle response) after its all ported and stuff you will need a 35mm or 36mm carb and get some new tires and a set of shocks. if you have dough left over get an extended swinger or a arms. you do all this and that 400ex wont stand a chance
 
to beat a 400ex your gana need some port work a good pipe bigger carb good air filter get the head moded jet it and you should come close
 
ok would dropin in a 2000 yz250 make her move coz i can get a good one 4 300euro and 700 4 other mods 4 the yz would she move
 
A motor swap in not a simple thing. You will have to fab up motor mounts and other brakets. You have to make sure your motor is lined up rite. If your front sproket is not lined up just rite with the rear, you will have a chain that wil break, jump off or wear very quick.