i was just wondering how hard it is to install a race cam on my 2000 400ex. i have rebuilt an lt 250 motor before so i have a little bit of experience but the only 4 stroke motors ive worked on were like briggs 3-5horses. is there anything that is very different in a 4 stroke that i need to know. and how much gain does a low-end woods cam give, and how much gain does a top-end race cam give to it in estimate?
thanks

 

i don,t think you would gain any torque/bottom over the stock cam.a race cam will give you about 2hp on top but at the exspence of 4lbs of torque on the bottom.i've tried an xr400 cam and a race cam and have done tons of dyno simulations and i think stock is best for bottom,the xr is mid(all around and is equivilent to a trail or all around cam,s from white bros or web cam,but way cheaper right from honda)and a race cam(or hrc xr 400 cam from honda)gives you top-you lose bottom.My honest and tested advice-buy the xr cam,it's way cheap and works great the trade off (you gain more top than you lose bottom.IF ANY ONE EVER CLAIMS MORE THAN A 2HP GAIN FROM ANY CAM_THEY'RE LYING-ask engine builders or dyno testers.go for the xr ,it drops right in,uses stock springs and rockers,keeps the compression release(longer starter life/easier starting,exspecially when cold),it's half the price,a quality HONDA part and works awesome-i like it better than the race cam!think about bumping up the compressin too.you can bore out the cyl. 2mm to a 416 and raise the compressin to 10-11 to one pretty cheap.

 

Funny you should mention these mods, this (little bigger bore with increased compression and an XR cam) is exactly what I was planning for my bike later this month.... Do you have any lift, duration, etc.. figures for any of the commonly avaliable cams?

Anyone know if I can get away with 11:1 in a 400EX on pump gas (92-93 octane) with a little bigger (XR) cam? I think I should be able to, but every engine is different....

 

i run 11to1 compression and am at 217psi(many other mods)and don't have any problem's using pump gas.i used 87 once and it only pinged when i lugged it in 3rd gear.92 should be fine.i also use octane boost-better power and way more over rev but i don't need too.i'm also in ontario canada so our gas is diffewrent than in the states.

 

hmm.. gabe i'm in that market too... only thing i need to know is... everything that i'll need and an estimated price for each individual part.. I cannot find a website ro any individual that can give me this information..

I'd liek to go with a 416, with a RELIABLE cam, and everything else i will need... I don't want anything that MIGHT BE OK FOR AWHILE.. if i haev to get new springs or something then i need to know that too.. I am not very knowlegeable about this type of proceedure.. thx later

 

Check out my mods on my web page, as far as the cam is concerned I got mine from web cam. xr 400 grind. Get ahold of lauri at web cam and she will help you with any questions you may have. I have also bored mine to a 426 with 11:1 piston. I have no trouble using pump gas but I am at around 4500 ft. I also feed with a 39mm fcr carb. Its a great combination. I have been running this setup for more than a year now with no problems..
My best advise for installing the cam is to get yourself a honda manual for the 400ex and use it. It is a great manual...
If I can be of any help please email me and I will get all the info to you as I can.

http://www.trxoutlawz.com

Later
Chuck

 

Gabe - I'm running a je 87mm piston (416cc) with 10.5:1 compression. With pump gas 92-93 octane, I seem to have little or no problem with predetonation. Occationally, I will hear a small knock with certain brands of gas; even then I only hear it when I lug the engine and it clears up quickly as the rpms increase. One other thing, I was advised to use a je piston rather than a wiseco piston. It seems that a wiseco piston is designed more for a race engine that gets rebuilt regularly. The je tends to hold up considerably longer I'm told.

With the hotter cam, you may want to consider hardened rockers.

I did this project in june, and it really didn't take that long; maybe 4 hours to get the cylinder off and about 6 hours to get everything back together. It REALLY wakes up the 400, you will be pleased - no "I took my airbox lid off and it seems faster" placebo effect here; it really stands up and says hi.

ogre

 

trx-outlaws:

Way cool page and bikes.. Couple questions tho...

Did you get hardened rocker arms? or springs? and what type of cam did you get? race cam or normal? or an xr400? did you port or polish anything. And last but not least, does the big gun stick out past the grab bar causing the pipe to be ripped off when you wheely?

 

Which XR cam is this exactly that you put in the 400EX for better performance? I am interested into making my 400EX more powerful on the track, What all can I do engine wise, high comp piston, cam ... that is relativley inexpensive. I dont care to spend 15 hundred dollars on it. Can I get it ported to help out. Rev chip? I just need like some good information and opinions from you because you sound like you have the expirence in this matter. Thanks alot

 

I got the 450/451 grind from webcam. No I did not replace the springs or have the rockers hardend. I have had no trouble at all.. The Big Gun does not stick out past the grab bar. that was only on the prototype.. The newest ones have been shortened and hpc coated for less heat and the headers do not turn color.
Yes I did do some porting. The intake and exhaust ports are very mismatch from the factory. At the very least smooth these up...