I was looking at buying the xr400 cama nd upping the compression by changing the piston those of you who have done the mod what are your opinions would you do it again or would you just leave it alone what all needs to be changed to switch it over and why dont you have to change to hardened rockers or do you let me know what you feel about this mod and where does it put the power range more up top how much bottum end do you lose

 

i have a wiseco 10:1 AND A XR 400 CAM AND I LOVE IT its a very combonation in my oppion there was no bottom loss at all it is so minimal that i cant even really tell the reason that you DO NOT have to hard face the rockers is because most aftermarket cams are made of a harder material thatn the stock one so they were out the rockers bad but a xr cam is the same material so it wont ware them out any faster than stock i did all these mods in no time at all but if you buy a cometic top end gasket beware they dont come with all the gaskets you need it only come with the head and base you will need to buy the sleeve o-ring and the cam chain tensioner gasket and the head cover gasket and a cam chain tensioner o-ring i also recomened pipeing your bike(full system not just the slip on) and using a k&n filter or some other method of getting more air into your motor and if u can afford it buy a quicksilver carb there great hope i helped you out have fun

 

Here is the exact copy of a post I made about 1.5 months ago on another site. Same holds true today, you will be very pleased with the setup. Personally I would go with the JE piston, but that is my personal preference.

To all those who are looking for info on a cammed, stock bore machine I did just that about a month ago and you will be more than pleased. I decided to go with the stock bore, as I felt that boring a perfectly good cylinder was not necessary. The stock bore will also tend to run a bit cooler than a 416, but it definitely runs hotter than the stock piston.

I decided to run the stock bore 10.5:1 JE coupled with the xr400 cam and gasket. I did all of the teardown myself and did some minor port work while I was in there. Basically cleaned up and port matched and polished the exhaust ports. I also ported the headpipes a bit where the welds were. I have been running a White Bros slip on for well over a year and am satisfied how it works with the modded motor.

First impressions were that the bottom end is really unchanged. While pulling through the midrange, the cam really begins to unwind itself letting the motor pull much harder than stock. Before I short shifted to keep the motor in the meat of its torque range, now she just pulls hard right to the rev limiter. I had only hit the limiter a few times with the stock motor, but now I find myself rev happy and hitting the limiter more often. I have not ridden a 416, but I am more than happy with the setup I have now. If the motor lets go (it probably never will, it is a Honda) I will be able to bump it to the 416 instead of re-sleeving it. Please feel free to ask me any questions.

 

2000, how much does the higher comp piston & xr cam run??

 

The cam from service Honda was $120, top end gasket kit $26. I believe the piston was $136 plus shipping. Total of $282.

 

Go to the exriders.com and hit the link to Marcums atv i think they are cheapest around. Plus the owner will help in any way he can. I think i got my piston for $125 with the gaskets.

 

All advice here is good just wanted to point out one thing the stock cams and the aftermarket cams are made of the same matrial. The web cam is no more than a stock cam welded up to height and reground to the duration and lift that is needed for the wanted gains. the reason for the hard faced rockers is because with a high lift cam the requires heavier valve springs there is more stress put on the rocker and the stock black heat coating with begin to flake off getting into the motor. I have a 416 kit in my wifes ex with the web alround cam and am very happy with it. I also use that cam in my 440 and it has also done well there although the big grind cam would help give it more topend.

99 416ex
JE 10.8:1
web cam
big gun full system
K&N filter
Dynojet kit
pep dampner
and more
99 440ex
flow ported
39 mm fcr carb
K&N filter
sparks rev box
big gun exhaust
strongarm a-arms
durablue 2+2 axle
elka triple rates with ssd alround
and much more

 

It might start out as a stock cam but when they do the welding they use a differnt metal than the cam. So when they are done the cam lobs are harder than the rockers so you have to get welded rockers(harden rockers) to match or else the harder cam lobs will eat up the softer stock rockers. This is how i had it explained to me. If i'm wrong please let me know. Thanks for your time.