400ex Rebuild

[JustinD]

I want to freshen up my 00 400ex and probably will go with a big bore kit. I don't want to loose the reliability I thought maybe a 426 or 416 kit. About how much will I spend on this project? I want to Do it right everything I need.

I pass those KFX Z 400's!!!!!!

[SandShark400]

plan to spend 260 + cost of jet

[04'400ex'er]

Are you wanting to just do a bore or are you going to put a cam in also and have the head ported and polished? are you going to do all the work yourself, less the boreing? all this will make a difference in the price. 416 will be the most reliable of the kits, but the 426's are usually fine. If you do this build right and put all the best products in It could cost you a grand. If you just put a 416 piston in yourself you could get it done for around $200.

[FoxRacing81]

Least amount of money would definalty be the 416. Not as powerful though...

I'd go with about a 10:1 compression piston, and just bore your cylinder out, get a nice hotcam, jet it well, and you'll be happy.

Reason I'd say 10:1 comp is because unless you wanna spend money on getting a new rod or crank and having it installed, you won't wanna go over 10:1 IMO, some guys run 12:1 440s on stock rods/cranks and don't have problems, but I myself would not want to risk it.

I have a 426 11:1 ross piston, hot rod H-D crank, hotcam stage1, port and polish, and she runs nice.

Cost should be around 250-300 including machining and such.

-Justin