I was wondering if anyone had any experience with the White Brothers rev limiter on the Honda 400ex. The magazine 4-Wheel ATV Action radared a stock 400ex at 64 mph. They said that the 400ex "...signs off too quickly on the top end (a White Brothers rev limiter easily solves that problem)...". What kind of top speed gain can I expect? What is the stock rev limit vs. the limit with the rev limiter? How much does the rev limiter cost? Is it worth it?

Any help would be appreciated.

 

I am around 75-85 now with the White Bros. CDI. Stock Honda is like 9100RPM's With the WB it is about 11,000RPM's The CDI is like $180... I think

 

Thanks for the info Skunky. It seems like the WB rev limiter would be definitely worth $180. I just wanted to be able to get 70 mph out of the bike.

 

where do you order the rev limiter from.how hard is it to install.Also ever sense i put on my FMF powercore2 and jet my 2 gear seem to run out real fast will the rev limiter help that out some

 

You can order it from whitebros.com or rockymountainatv.com or you local shop can order it for ya. ANd that is what it is all about i can rev higher as you can see by my mods the rev helps

 

The White Bros. cdi box boosts the stock rpm from 9300 to 10300, can the stock springs handle the increased load? Or do you have to replace them? Also, how easy is it to install the new cdi box? Your replies will be appreciated. Thanks. TRXMike

99 400EX, E-series muffler, 155 main, k&n filter w/outerwears, red maier plastic cut fenders, works triple rate, burgard a-arms +2 inch.

 

The rev box actually costs about $120. It takes all of five minutes to install, if that. All you do is look under the right fender and unhook the factory unit and plug in the WB. Your bike was manufactured with a large "cushion" when it comes to the rev limit, the stock Valve springs will not be affected. In fact the 400 can handle some fairly wild cams with the stock valve springs, not many bikes can say this.

 

This topic was discussed some time ago, and I believe it was found that the WB rev limiter is no more than a stock XR250 CDI sold under the White Bros name. I also remember that someone actually took the WB unit apart and found some numbers inside which did indeed cross reference to the XR250 unit. If anyone remembers this, or knows more about the WB rev limiter, please let us know. If I'm right, then you can get the XR250 rev limiter from any dealer (I think it's about $80), and save themselves some money. Also, I believe either unit only raises the max rpm by about 1000.

Search back through the archives a

 

I have the part number for the xr250 cdi from that topic, its 30410-KCE-671. Has anyone tried using the xr cdi box? I called CT Racing today about their cdi, they said that it is only 1000 rpm higher than stock and its the same as the white brothers.......

 

I have a friend who has a slightly modded 400EX...10.5:1 Wiseco piston, cam, 39mm carb, and the XR250 CDI. He recently moved, but had told me the CDI made a small difference after the piston and cam mod...but it was the carb that really woke up his motor. As far as I'm concerned it seems to be settled about the White Bros. and CT Racing CDI...both are re-boxed XR250 CDI's that bump the rev limit up 1000 rpm's. Save some money and get one from a Honda dealer.