300ex 250x rev box cdi

[r-exrider0003]

me and my friend were messing around, hes got a 250x w/ some motor work i think its bored to a 300 pretty much...well we were racing and ide get him of holeshot but on top end as soon as my rev limiter kicked in he would pass me, so we switched rev boxs, and the 300exs have a extra wire that the 250xs dont, it worked with the 250x cdi box, and didnt make really any differnce, so after we switched back un hooked my wire and it still started and ran fine, and what i am wondering is what is this small wire for??the rev limiter kicks in the same so i thoght it was for reverse, i tryed it and it was the same, so does any know what that lil wire is for???And also i was wodering if i should buy a aftermarket rev box for mine, do u get more power and speed for the money???One more thing, if i take out my choke for more air flow will i be able to tell any diffrence?thanks for any help:D :) :D

[atvridernc]

dunno about the rev box, im wantin one myself. but i took my choke out and i can barely notice a difference. maybe 1/4 to 1/2 hp increase. but i need all the power i can get and any little bit adds up. i have never needed my choke since i took it out.

[stonerider250x]

the extra wire prolly hgas somthing to do with the electric start on the 300. and the reason ur rev limiter kicked in before his is because the 250x box allows revs 100 rpms higher....noy much but there is a little difference

[dork]

so you're saying the 300 cdi worked on the 250x and vice versa?