I am planing on building up the EX now..
I need to know what parts to consider/need when doing it..

Seals
Cams ( Hotcam 2 ) trails/woods (low to mid power)
Piston I want to run pump gas so nothing higher then 11.5
Bore? 416? Sleave? I assume I dont need to bore the motor with the sleave? Just pull the old out and put the new in?
Rockers? When to get the hardened rockers?
Shortend valve guides??
Exhaust - Not sure yet but I want a full system
CDI - no
Carb - keeping it stock

Best of all TCS suspension [img]i/expressions/face-icon-small-smile.gif[/img] Not going to change the arms or swing arms...

 

It all looks like a nice set up and should run good. I believe with the Hotcams you won't need hardened rocker arms or shortend valve guides.
The CDI.......Is that like a rev limiter or some kind of ignition system control? If it is you may want an aftermarket rev limiter cause I use to never hit mine when I was stock but now I hit it often and your set up will hit higher Rs than mine.

Oh Yeah, one more thing. When you install your cam watch them head cover bolts, they are cheap. I had my torq wrench set at 7ft. pounds and broke/stretched a few of them. Could have been my crappy torq wrench though.

 

Mudstud, from experience, I think there are three ways to build a 400ex engine.
1) full stroker/high comp 460+ crazy
2) 440 ex full build
3) 406/416/426 bore ,up comp., new cam, ect.
#3 sounds like you.
Raise the comp to a true 11.5 to12.5:1 depending on your fuel opinions/availibility/budget. You should be able to reuse your sleve, if not there are millions out there.I say true comp, because many kits had/have been set up with an XR400 engine in mind. Just ask I believe Ross JE and Wiseco all offer what you want. If you go over 13:1 I think you should beef up the bottom end, so don't go there unless you want to. Hot Cams stage 1 is lower RPM band, stage 2 upper, you decide. You can also run a web, megacycle whatever with out hardening the rockers if you run a oil cooler (FST has one) they dump cool oil right on the cam, I know a guy with this set up (web cam) with years on it, no wear on arms. I say keep an eye on it, as he does, but I think you can get away with it. The rev boxes are a waste IMO. This engine is done making power (unless you go high rev full race drag type set up) before it needs another 1000 rpms. The curve is good, and it will be hard starting when cold. Get a nice full pipe, LRD, HMF, DMC.
Your good