okay so I don't have the money right now or even the need to modify my new 400EX. but in time I will definatley need to do something to add some power to it. I was thinking of doing two things and was wondering what you all think. White brothers(and probobly others) has a 4 stroke power up kit. it comes with a new cam pipes k&n jets rev box and it seems like something else but I cant remember what. this runs a little over $800. THe other thing is the 440 bore kit. Say I put the power up kit on first then later decide to do the 440 kit. will i need a different cam and pipes? I will be doing some trail riding and more dune riding.Thanks for any info on these things or If you have any other Ideas!!

 

if you want fast and reliable go with the 416 kit instead of the 440 they will put out about the same power and youll get the better reliablity with the 416 ( since you can bore it to 440 next time if there are any problems.

for the best power go with

- XR400 cam, or a cam where you dont need hardface rockers.
- JE 416 kit from marcums atv, great deal for $165 which includes the boring.
- port and polish the head, important if you want the full power of the engine.
- 39mm FCR carb, in combination with the port and polish to make it rip.
- Sparks X-6 full exhaust to let it breath the best.
- probly get 40+ hp out of those mods

you could go without the port and polish and fcr carb, but you wont get that much power out of just the 416 kit with the cam, if you put all that into the motor most piped and jetted raptors dont have a chance.

 

That sounds like a good plan. anyone else have any good ideas?

 

You wont get 40+ HP.....

I have all that done and i gained maybe 10. I am around 36-38 if i am lucky. Another thing they dont polish 4-stroke heads because it dosnt make a diference. If you want 40+ hp do a 440 with 13:1 compression. Look at my sig i have about 3k into my motor and it still isnt fast enough [img]i/expressions/face-icon-small-sad.gif[/img] Cheapest way to gain power is to put a 14 tooth sprocket on it.