400ex big bore kits

[mar400ex]

I have a 400ex, and I want to put a kit in it, 4-stroke tech makes a 500 kit for it, but I've heard that the compression gets raised too much when putting it in and you have to rebuild the top end too often. Do you guys think the 440 or the 465 would be better?

[member]

mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmk

im guessin your not serious into riding? OK well first off, what type of riding are you most interested in??

[Thump_It]

Why do you say he must not be serious about riding? What kit should he get? I also heard that the 500 kit raises the compression quite a bit. Correct us if we are wrong. Thanks for you help.

[mar400ex]

yea, I'm new to riding and I just want some advice on what to do here. I will be riding mostly in the dunes.

[member]

Originally posted by mar400ex
yea, I'm new to riding and I just want some advice on what to do here. I will be riding mostly in the dunes.


alrighty dunes it is! installing the 500cc kit does not really raise compression, what raises the compression is how close the top of the piston is to the head, so just boring and stroking will not raise the compression, it all depends on if you stroke it if you put a shorter connecting rod in or what not.. now if your on a budget i would suggest just like a 426 or 440 kit, but if you have the time and the money, a 500 would be pimp, but sinse your gonna be in the dunes you dont want heat to be a problem, so if your pretty much happy with the stock performance and are lookin for a little more power i would just get a pipe, air filter and a 426 kit with a new cam and maybe a port and polish, now everyone will tell you to send your head off to be ported and polished, but its not hard to do if you have a dremel tool and some patience!!! just look up some articles on port and polish jobs, i promise you its easy and simple, and not worth the 500 dollars most companies charge, so how much more performance are you looking for?

[mar400ex]

well that all sounds good, and it has a pipe and k&n and all that on it now, but I want the most power I can get and I want to go as fast as I can. If heat can be a problem, then what's the solution to it?

[member]

for heat there are alot of things you can do, over sized oil coolers, 2nd oil coolers, air scoops, and oversized oil tanks, now im not exactley a guines YET lol so give 4 stroke tech a call tell them you are gonna be riding in the dunes, tell them you wanna go really fast, and then tell them your budget im sure they will help you alot more than i will, i dont have a phone # off the top of my head but im sure its on thier website, and also i think mickey dunlap is actually a member on this site, im pretty sure his name is Mickey Dunlap, so shoot him a pm