Rocker arm help on 400ex

[skip426]

2003 400ex. installing a wiseco 426kit 10:1 with the new stage 2 hotcams cam, port and polish on the head with kibble white valves and springs. I have a AMR CDI also but not sure I'm going to use it. Stock headpipe with a big gun slip on.

Question is------ Do I need hardened rockers for this set up or not?

Any help is appreciated. Thanks, SKip:)

[sixer3]

Originally posted by skip426
2003 400ex. installing a wiseco 426kit 10:1 with the new stage 2 hotcams cam, port and polish on the head with kibble white valves and springs. I have a AMR CDI also but not sure I'm going to use it. Stock headpipe with a big gun slip on.

Question is------ Do I need hardened rockers for this set up or not?

Any help is appreciated. Thanks, SKip:)

nope sure don't

The webb cams require it because they hard weld and regrind stock cams which makes the surface of the lobes on their cams harder therefor they need to match it on the rockers to prevent uneven wear. your hotcam is good to go

[skip426]

Cool. I was hoping not, but wasn't sure.

Thanks alot! Skip

[tri5ron]

you might also want to do a search on grinding the internal welds on the stock headpipe. It's not the same increase in flow as some of the more expensive exhaust systems,... but it IS free to do, increases a little more flow than the stock headpipe, and since you will also be needing to rejet anyway, you might as well get as much "gains" as is possible.

you might also want to consider installing a +6 timing key, (since your staying below 11:1 compression),
and a 450r carb while your at it.

btw- keep the stock revbox.
The aftermarket ones do not provide any beneficial gains for a 400EX, and are just a waste of money.

your quad will run rather impressively, compared to stock, and you should be somewhere around 34 to 35 HP when your finished.
(Provided you get your jetting spot on).

Thats not too bad, for still being able to run on straight pump gas, AND still having a VERY reliable running quad.

Good luck with your build, and be sure to post your results when you get it done.

(just my .02 cents).

[2001400exrida]

the aftermarket rev box gives the 400ex more throttle response as well as it curves the timing.

[DragonGunner]

I have a Web cam an had to buy the hardend rockers...as said, your cam won't need it. I'm not familiar with your brand CDI, if you can't tell the differance between it an the stock then thats not good. I have only used the White Brothers CDI for the last 9 yrs. Anyone want to come to my house an ride it with stock CDI, then ride with White Brothers CDI your more than welcome...you will buy a White Brothers CDI.

[skip426]

@ tri5ron.
I've heard this alot about the Rev box from long time racers. I had it laying around and thought i would try it. I've also heard they can make your quad hard to start when cold. If this is the case it'll get throwed back in the pile it came from.
Anyway, thanks for the heads up on the exhaust, the thought never crossed my mind but it is a hell of an idea. I'm hopng to have the build done in the next month or so and will post before and after pics.

Thanks, Skip

[DragonGunner]

Originally posted by skip426
@ tri5ron.
I've heard this alot about the Rev box from long time racers. I had it laying around and thought i would try it. I've also heard they can make your quad hard to start when cold. If this is the case it'll get throwed back in the pile it came from.
Anyway, thanks for the heads up on the exhaust, the thought never crossed my mind but it is a hell of an idea. I'm hopng to have the build done in the next month or so and will post before and after pics.

Thanks, Skip

My CDI rev box is hard starting in extreme cold, it takes a little more juice, but if your battery is in good shape it may be easier, spring, summer an fall never a problem. A few time when it was around 10 degrees I just slip the stock cdi on an get it started an warmed up an then switch to the rev cdi an go riding in the snow.