I have a 04 400ex and was lookin for more power and was wondering how you install a hot cam and what you need to do it and if its worth it thanks

 

Installing just the cam won't do a whole heck of a lot. If you throw in a higher compression piston (which you can get for about $120), then you will notice quite a change in the quad.

Both can be done pretty easily with the shop manual, if you have half decent wrenching skills.

 

will the cam still help with a power increase or do i really need a high compression to see any differences

 

Personally, I think you'd be disappointed with the results of just the cam. While you have the motor opened, spend the extra to do a piston. You'll be all smiles.

 

will the cam and piston cause problems on down the road or is the engine still reliable with these moifications to it

 

you can make a reliable bike. just run around 10.5:1 compression on a stock bore, 406 or 416 and you should be good to go for a very very long time.

 

Since it's a brand new bike, you could go with the stock bore 11:1 piston and save those rebores for later and save little cash. They say you should hone the cylinder before you drop in the piston so the rings will seat right.

 

I put a stage 2 hotcam in my friends 400ex. His other mods are a fmf pipe and open airbox with K&N. With the cam it gave a lot more mid range and top end power. The engine wants to keep reving now, it doesnt level off like before. The only downfall is he lost some low end power. To fix this he bought a 39mm fcr carb. The carb gave a nice gain through the whole power range. Plenty of low end, pulls good all the way through top end.

He did not want to change the piston yet, these mods worked very well togather. Im sure a high comp or big bore piston would help out quite a bit.

 

i am considering these mods also, what is the best brand piston, also how much money am i lookin at to get my first bore done?

 

actually, do I even need to get it bored?