alright guys right now ive got an 03 z400 with a full yosh pipe, intake, jets, open air box and some aftermarket sprockets. i keep up with pretty much all stock atv's besides the new 450's. raptors i pull on like its my bikes job and all other stock 400's cant touch me on the trails. The 450s dont pull that much until i get top end when the bike tops out at about 72ish. I love the way the bike pulls compared to the stock sprockets and wont go back to get that little more top end unless i can make some more power lower end. I was thinking something along the lines of a bigger carb or a cdi box. What do you guys thing?

I would love to get the big bore kit but then i dont see the bike being nearly as reliable as i want. I also dont wanna upgrade to a 450 due to me loving reverse and loving sitting a little bit higher so i dont bottom out nearly as much as the mx 450's. What are some pros and cons about both a cdi box and a bigger carb? ive heard ill mess my piston up with a cdi box but i want to hear what other people have to say

 

with my drag racing experience ive learned that weight and wind drag is a big component. if you want more on the line then cut off all the excess plastic that you dont need, and cut or put race cut fenders on it for less wind drag. a bigger carb and a cdi box will help, but if you wanna really stretch for power then you will have to bore...

 

For low end grunt, a higher comp piston. Maybe a mild cam.
I consider the CDI a higher rev option and no low end result. Same with the carb. I could be wrong.
The 1000 rev cdi would give you that lil extra on top.

 

bore it to a 440 or a 450 and a set of cams with a good CDI box and it wont hurt the motor. now you can even go bigger up to a 535cc stroker but its big bucks and not that dependable, and you dont need high compression unless you have the money for race fuel. I run normal gas in mine and went from 26hp to 44 with doing a big bore 440 with cams and cdi with a 41mm fcr carb

 

who does performance work on atv's? im not into the mx scene at all and only trail ride but i want some more power. ive really considered a big bore kit but does it make more sense to bore the engine out?
also what is a fcr carb? i looked at some carbs the other day and they are mainly around 300 bucks (give or take)
and another question, mucky roughly how much did your setup cost you?

 

I had mine bored and resealed.12/1 je piston. ported and polished. cams and Keihen FCR 41mm flat slide racing carb all for around $2100. the carb is around $500. I had the 470 kit in it once and the cylinder and piston cost $900 untill the sleeve cracked. thats why I had it bored. it does cost a little more but I think it's worth it. Ive got close to $20k in the bike now and its never ending

 

wow, i would love to be able to do that kind of work with my z but ive got a 550whp STi thats gotta all my money tied up in that.