Which cam??

[400exMO]

I'm wanting to get alittle bit more power out of the 400 so I'm gonna get a cam. All motor mods I have are a slipon and a K@N. Which cam is the best for that application?

Also i'm wondering while I have the head pulled is there anything else I should replace/inspect. Or anything else that I should buy with the cam.

I plan on getting the CRF Chain with the cam but anything else?

valves sinse the top end is took apart.

[400exMO]

Go into detail plz.

Originally posted by 400exMO
Go into detail plz.

Check if their out of adjustment.

stage 1 hot cam OR get the xr400 stock cam its alot like the stage 1 hot cam but way cheeper (used).

The 400ex stock cam is all bottom end. The xr cam is set for mid to top end gain.

But if your going new get the stage 1 hot cam. Its for stock motors and you gain bottom and mid.

If you plan on going with a high comp piston some time get a stage 2 hot cam for mid to top end gain.

If you plan on highly moding the motor get a hot cam stage 3 only if you plan on doing the mods right away.

You should buy aftermarket valve springs if you plan on getting a cam.

Also in a mag I was reading it said when you change a cam on a 400ex they recomind that you hardweld your rod. I dont think the rod would actually snap from a cam but who knows.:confused:

[400exMO]

Anyone else have some input, need some help!

[underpowered]

Originally posted by slow
Check if their out of adjustment.

well first of all you are gonna have to adjust the valves to the specs of the new cam, so that is a given. but dont just go hanidn out info when you have no idea what you are talking about.

you do no hardweld your rod. no one ever does that.

some cams require that you hardwled your rocker arms. Web Cams regrinds stock cams and actually harden the cam. since teh cam is harder it will wear your rocker arms and therefor they need to be hardened as well, through a process called hardwelding. do not mix a hadweld cam and stock rockers or vise versa because it will cause premature wear.

as for cam choice, it depends. I would suggest adding a high comp piston while you have your bike apart. even a stock bore 11:1 will give a good gain along with the cam. you will see some gain from just a piston, and some gain from jsut a cam but if you do both it will give you a decent overall gain.

a stage 1 cam is usually a low end cam, made more for woods riding. stage two is usually mid-upper power for mor high speed riding like MX. hot cams stage 3 is a knarly grind that is alot of top end for big bore/stroker motors. the XR cam is a cheap alternative that give some gain mainly in the low-mid range. there are otehr companies that offer cams, and each should have a short description of where they add power.

If you plan on doing further mods down the road (i.e. Big bore, Port and polish, Full exhaust, Stroker, ect..) i would get atleast a stage 2. if you plan on sticking with just a pipe and a stock high comp go with whatever you think will be best for your riding.

[krt400ex]

Originally posted by slow
stage 1 hot cam OR get the xr400 stock cam its alot like the stage 1 hot cam but way cheeper (used).

The 400ex stock cam is all bottom end. The xr cam is set for mid to top end gain.

But if your going new get the stage 1 hot cam. Its for stock motors and you gain bottom and mid.

If you plan on going with a high comp piston some time get a stage 2 hot cam for mid to top end gain.

If you plan on highly moding the motor get a hot cam stage 3 only if you plan on doing the mods right away.

You should buy aftermarket valve springs if you plan on getting a cam.

Also in a mag I was reading it said when you change a cam on a 400ex they recomind that you hardweld your rod. I dont think the rod would actually snap from a cam but who knows.:confused:


u do not need new springs if u r going to get a stage one. i talked to the guy at hotcams and he said that the stage one will produce mid to top end gains without causing any loss in bottom end.with a slip on that is ur best bet.


also wherever u heard to hardweld ur rod, they r way off. that is not the least bit nessecary. u should get a hd rod if u plan on getting really high compression piston or doing a bore job, but that is it.

if u get anything else than a hotcam, then u will need to hardweld ur rockers. the hotcam is designed to work with stock components. most other cams r not.

[400exrider707]

I ran a hotcam stage 1 in my EX with the same mods you have now. At the time I also put in a wiseco 11:1 piston (although for this application I would choose another piston) THe 02CRF cam chain is also another nice addition, so be sure to do that. Have your valves checked for wear and replace them if necessary, also valve seals are probably a good idea while its apart, and dont forget a top end gasket. I recommend getting good gaskets as the junky ones (ie tusk) will leak in no time at all. I went with a thin cometic head gasket. You will really like these mods.

[400exMO]

400exrider707 could you go into alittle bit more detail on the valves? My stepdad and I are both mechanically enchlined enough to do all the work ourself, we just need alittle bit more info on what to get and what look for.

Also you guys were suggesting high comp pistons. I would would want one but would need to stay on 91 octane gas. Also would a high comp. piston cause anything to break sooner than it should. I want my quad extremely reliable with alittle pop.

[stocktires]

An 11:1 piston will run on 91 easily, my 12:1 runs on 92.
I'd suggest a small cam like the XR cam and the 11:1 piston. Take you head to a shop and get them to check it out, and make sure it's in spec.

[cals400ex]

the hotcam stage 1 is a little more aggressive than the xr cam if i remember right.....and the stage 1 isnt' very aggressive if you ask me. if it was me i would get a good full exhaust and sell the slip on, stage 2 cam, and a thin cosmetic head gasket. the other problem with the stage 1 cam is that it is kind of loud. we didn't care for that.