440ex big bore

[motoxmitch]

i am desiring to get a 440ex kit for my already well tuned 400ex..it has curtis x-4 system, advanced key on flywheel, high rev ignition box, stage 2 cam(white bros), k&n with jet kit..im wanting to get a 440 kit WITH aftermarket valves and valve springs..does anyone know where i can go to find the valves and springs-aftermarket? also, im kinda curious of the reliability of the 440 big bore kit...is it good for a few races? reccommended or not?

[underpowered]

for the valves and springs get Kibble white Black diamond valves and springs. Reliability on the 440, it varies. It depends on how the motor was built, broke in, and ridden. some 440's will last forever, but i have seen other last only a few rides.

[cals400ex]

i would probably do a smaller bore such as a 416