400ex a strong 426

[ti-ex]

wondering what parts for the engine i would need to make my 400ex,a strong 426 motor,wonderabout valves,rockers,what iwould have to do port polish,springs.just wondering what i would have to do
thanks

[stupid driver]

Heres the list that i can think of.

Bore cylinder
new piston
port/polish
more aggressive cam
new gaskets
full exhaust ( or slip on if you prefer)
better breathing air filter
i bought a 39mm fcr carburetor when i did my 426. It is not neccessary, but i did notice quite a difference with the carburetor. Just my .02

[Steve-o 400EX]

Originally posted by stupid driver
Heres the list that i can think of.

Bore cylinder
new piston
port/polish
more aggressive cam
new gaskets
full exhaust ( or slip on if you prefer)
better breathing air filter
i bought a 39mm fcr carburetor when i did my 426. It is not neccessary, but i did notice quite a difference with the carburetor. Just my .02

Yea thats about it, instead of the 39mm, if u get your stock carb bored to 38mm it will give you the same effect as the 39 but for half the price. When you do your gaskets, dont use a base gasket and only do one thickness on the head gasket, it will give you the true compression that your piston says.

[YZ400EX]

What is the big deal about not using the base gasket and only using one of the head gaskets?? I mean what real effect does it have power wise besides giving you true compression? I mean it sounds to me like it would create more of a hassle, but like I said I dont know because I never did it..If those gaskets were not needed why would companies sell them and why would anyone need to buy them?? just asking..

[Steve-o 400EX]

Basically it just gives you real compression which gives you a little more power. Its not really a hassle, its actually easier, companies dont send their quads out like this just because they are doing every measure to make sure that the motor will last. Thats the deal with that, i think.

[YZ400EX]

See thats what I am saying, why wouldnt you want your motor to last like they would from the factory..I mean why take the chance of blowing a gasket or leaking oil around the base just to gain maybe a small amount of power to have your true compression..To me it just would be easier to put gaskets in and save me time later down the road..JMO though..

[Steve-o 400EX]

Yea, i see what you are saying, i am saying that the factory takes extra care on what they do because they have to warranty it, any time you touch your motor the warranty is voided. In my opinion there is no more of a chance of anything happening if it is done correctly. You are not just metal to metal on the base, you use a synthetic style gasket, almost like a hardening gel.

[cals400ex]

if it was me i would just run hondabond on the base and a thin cosmetic head gasket. we also has some problems running 1 layer of the head gasket. we got it right before but sometimes it takes more than 1 try and it is a hassle to fix. even though it is a simple fix. all of my buddies do not run a base gasket. we all run hondabond on the base. not one of us has had a problem with that.