Need some help!!!

[mrnate400ex]

The ol' stock motor isn't what it used to be. So, I'm looking to rebuild. I have decided on a 426 kit and probably a stage II hotcam. I also think I am going to put a yz426 carb on it and do some port work. Here is my couple of questions! What throttle cable will I need to make that carb work with my thumb throttle?? And, should I get a weisco or JE 11:1 piston?? Are the HD head studs recommended?? What kind of HP #'s are we gonna be talking about here?? I know I won't know exactly, but a round about figure!! Thanks!!

[firefighterjosh]

Originally posted by mrnate400ex
I also think I am going to put a yz426 carb on it and do some port work. Here is my couple of questions! What throttle cable will I need to make that carb work with my thumb throttle?? And, should I get a weisco or JE 11:1 piston?? Are the HD head studs recommended?? What kind of HP #'s are we gonna be talking about here??

I would ditch the YZ426 and go with a 450R Carb. (Look at the stickys under the 400 threads) I like JE pistons. I have one and have had no problems. I would get teh HD studs.

[mrnate400ex]

i've thought the idea of the 450r carb too, but i like the idea of the fcr. i've heard they are easier to tune, and have a better throttle response. i was leaning more toward the JE as well.

[Castor-426ex]

ive done both the 426 and the 416 engine setup and i definately reccomend JE or Ross racing pistons nothing personal also if this is the first time you have had the top end of your motor apart heavy duty head studs arent a must just make sure to use a good head gasket such as the honda xr or the oem steel flex gasket

good luck hope i helped

[johnsls]

I agree with the other replies.

should I get a weisco or JE 11:1 piston??
JE is what I have.

Are the HD head studs recommended??
DEFINATELY, I didn't know about this until after the install but so far so good.

What kind of HP #'s are we gonna be talking about here??
A LOT more than stock!! :devil:

Do a search on here for HP gains,, it on here somewhere.

Personally I would get a range of JETS, someone will recommend something like a 170 but get a range like 165 - 170 or 170-175

Good luck,, and the best advice anyone can give is.
BUILD IT RIGHT!!!

[foleyit]

I have a JE piston 12.5:1 in my 400ex and I haven't had any problems with it. Stage I or Stage II hot cam? I ride mostly in the dunes and open desert areas so I went with the Stage II.

I don't have an opinion on either a yfz426 or a 450r carb, but I have an FCR. The throttle response is real nice on the FCR.

Good luck hope it helps.

[Chino886]

The YZ426 carb is a 39mm FCR, you will have spacing issues using this carb. The throttle response is killer with the FCRs.

I have a 39mm for sale that is set up for a 400EX, no clearance issues.

PM me if interested!

[mrnate400ex]

thanks for all of your responses. how much have you guys seen it cost to get the hd head studs installed?? i know gt thunder has them and can install them, but i don't want to have to send it in.

[Chino886]

Originally posted by mrnate400ex
thanks for all of your responses. how much have you guys seen it cost to get the hd head studs installed?? i know gt thunder has them and can install them, but i don't want to have to send it in.

I have a set that I will sell you for $50, I never installed them but had plans to when I bored the cylinder.

Any machine shop could do it as long as they have a roll form tap.

[Chino886]

forgot pic

[johnsls]

Originally posted by mrnate400ex
thanks for all of your responses. how much have you guys seen it cost to get the hd head studs installed?? i know gt thunder has them and can install them, but i don't want to have to send it in.

You would still need to either take them somewhere or send them out.
I would think Colby at C&D Racing could do it no problem.. thats who I bought all my stuff from and had him resleeve my cylinder,,,VERY NICE WORK

[johnsls]

OH YEAH,, by the way... Chino sells good stuff,,, Free bump

[mrnate400ex]

Chino, is the fcr worth it?? what is the difference between the fcr you have and one off of the yz426?? what kind of clearance problems would need to be addressed?? this will be the first time taking the top end apart, so are the head studs really going to be a problem?? i guess i can try it without and if i end up blowing a head gasket down the road it wouldn't be much trouble to get the hd studs put in if i have problems. i'm also open for other cam suggestions. i prefer not to have to do the hard faced rockers and all of that so try to keep it "drop in" only. of course, i don't know of any others that are "drop in" besides the hotcams.

[Chino886]

The FCR is definitely worth it in my opinion, the throttle response is 10x's better with the FCR, plus if you are going to work the head, then you will need a bigger carb. With the FCR on my bike, it seemed to pull harder all through the gears.

The head studs are good insurance if you are going to bore it.

The cams....Hot Cams are the only drop in ones that I can think of, I had the "old" stage II cam and loved it. I think WEB makes a drop in cam, but they cost a bit more!

The FCR I have has a longer "adapter" to the airbox and longer from the motor to the body of the carb (sorry, I can't think of what its called). The YZ426 is very short on both sides, you will have clearance issues with your gas tank and you will have to move your airbox forward 1-1 1/2". I tried that with the carb I had and it put too much stress on the carb and I had it come off several times on the track, not good to say the least.

[mrnate400ex]

can you buy that adapter from the motor to the carb?? i know what you are talking about, but can't think of what it is called either. i would have to move the airbox forward anyway even if i used the 450r carb or the fcr.

[Chino886]

Originally posted by mrnate400ex
can you buy that adapter from the motor to the carb?? i know what you are talking about, but can't think of what it is called either. i would have to move the airbox forward anyway even if i used the 450r carb or the fcr.

When I was looking into it, the YZ426 carb does not have an interchangeable "spigot" that you can buy, you would have to have someone like NOSS Machine, make you one then make sure it was a smooth transition with no lip.......it was not worth my time.

The aftermarket FCRs have interchangeable ones where you can buy longer or shorter applications for your needs.

[mrnate400ex]

so the adapter is actually on the carb?? let me make sure i am understanding right. you are saying that the outlet on the carb can be taken off and interchanged with a longer outlet to work with different applications?? that's a pretty sweet deal if it what i think it is.

[Chino886]

Originally posted by mrnate400ex
so the adapter is actually on the carb?? let me make sure i am understanding right. you are saying that the outlet on the carb can be taken off and interchanged with a longer outlet to work with different applications?? that's a pretty sweet deal if it what i think it is.

You have it partially correct! On aftermarket FCRs, you can interchange the "spigot, adapter, or whatever you want to call it", but on the OEM YZ 426 carb you can't......I am 99.99% sure of it.

To have an adapter made from someone like NOSS Machine would not be worth the amount of money it costs. That is why I got rid of the YZ carb and went with one made for the 400EX.

[mrnate400ex]

i would assume to have one machined would cost well over $100 if you wanted it done right anyway. i see your point. what about the throttle cable?? will my stock one work, or will i need a different one??

[Chino886]

Originally posted by mrnate400ex
i would assume to have one machined would cost well over $100 if you wanted it done right anyway. i see your point. what about the throttle cable?? will my stock one work, or will i need a different one??

The stock one with not work because of the bent metal housing where it goes into the 400EX carb.

A 450R OEM throttle cable works perfect! ;)