cams

[Tommy 17]

I was wonder if this story i heard is true. can u put a xr 400 cam on a 400ex. if i do this to my quad what will it do to it power wise. how much will it cost and will i have to do any rejettin or gearing. thanks.

Well if you put it on a 400ex it won't do much,, you'll need to put it inside the motor..LOL

OK all joking aside,,,yes it's possible,,I've got one sitting at home right now to put in mine. What the best thing to do when putting a cam in a 4 stroke is to also get a higher compression piston to go with it,,they work hand in hand and the benifit of doing both will give you a much much better power gain than just doin the cam by itself,,Now You can just put the cam in but hell if ya got the motor tore apart ya might as well throw in a new piston, and like me get the head ported ,there are quite a few guys on this message board that have an XR400 cam and love what it's done for their bikes,,but they didn't just drop a cam in and be done with it, they also did other mods to go with it. You will need to rejet, and the cost of a XR400 cam is 120 bucks from Marcums ATV,,,

[Tommy 17]

Rico thanks i am plannin on puttin a 416 kit and a wiseco piston or sumtin of that sort into it too but i was goin to buy it piece at a time when i get the extra money and put it all in at once. when ur 16 moneys hard to find when u have to pay for gas and car insurance wit no job except workin for u dad at his own company. I think i may order that cam this week and the piston and stuff next month or so...

Rico,


Can't wait to hear the outcome of your new cam & piston, that is what I'm thinkin about doing. You are keepin stock bore right? Keep us updated!

[trx400ex]

i think hes doin a 416

[Tommy 17]

rico u seem like u know ur **** so where can i buy the 416 from and how much will it cost for me to get them to do it. i want a high compression piston the highest u can go b4 u have to run over 94 octane fuel. what should i buy. i dunno bc none else here has the kits and we all clueless on what to buy.

[max400EX]

Where does the XR400 give you power(top mid low)? What other cams do you all recomend?

Well WJW77 I've decided that if I want to be more competitive racing I might as well go with a 416 10.8:1 JE piston (cuz JE pistons are lighter than wiseco) and I'm gonna send my head to Marcums and have Terry Port and polish it, with a nice exriders discount,,,he emailed me today and said that he's working on a special 416 kit just for exriders members so everyone needs to hold off to see what kind of deal he's gonna have for us..

400ex21 you need to get your cams and pistons from marcums ATV nobody else will be cheaper,,I garauntee it..link to his webpage is at the top of this forum..

And from what I've read the XR400 cam works best in the mid ta top area,,which is just perfect for MX racing..and it's a simple drop in part,,no extry bells and whistles to make it work..

And a 10.8:1 piston is about as close as your gonna get to running on 93 octane,,,I'll be using some Klotz octane booster with mine just to kick it up a little. To be completely safe you could get a 10:1 or maybe a 10.5:1,,but you'll need to use an XR400 head gasket to keep the same compression ratio..due to the different sizes of the gaskets between an XR motor and a 400ex motor..

[MJNOVA]

I have a spare Curtis Sparks Cam---Brand new---Full race----It requires the hardened rockers and the shorter valve guides though. I have a used CC----Torque cam also.....

[max400EX]

Whats the best cam that you dont need to hardface and/or get a new valve setup for?
Thanks in advance