cdi rev boxes

[mad4106]

i been wanting to know if these rev boxes really work?! and how much of an horsepower gain can u expect from these and is the throttle response noticeable? What would be the best brand to get too?

[82toyota]

im going to buy curtis sparks racing high rev cdi box------1000 rpm higher than stock $115.95

[bkelley]

Most people don't think they are worth the money since our bikes make all their power within the stock 9100RPM limit. Only real increase is the ignition advance, and you'd be better off just getting a Sparks key for $30 to do that.

[DragonGunner]

I would suggest a search here on this...lots of info....some say they are no good, some swear by them......I swear by mine, 10 yrs experince with them, or that is one...I can only recommend White Brothers. I believe they were the first or one of the first to make it...in my opinion they got it right....I have no experience with any other brands....
The White Brothers does more than raise the limiter another grand, it changes the power curve as well.

[Carapau]

Hello people,

I have a CDI box diferent from everyone, since ever, in my Sportrax 400 2001, i have the cdi box from Honda, XR600, later i can tell you the part number. The rev limit i don know, but is later than stock, i usually dont rev the engine. And the power curve is better.

Recently i bought the fat boy 4, (i have the fmf power core + powerbomb), needs to jet now. I ask to my mechanic if exists other CDI box that o should buy, he tell me that this one is very very good.

Anyone try this cdi rev box?

Sorry my english.

Nuno from Portugal

[GTRider256]

I had I GT Thunder Cdi box on my 04 but I never really saw a difference. I saw much more of a difference when I changed the gearing

[ish416]

CDI rev boxes do what they say, they raise the limiter 1000 rpm.

You would be better off to change the gearing as your EX has already stopped making power around 8000 rpm and spinning it to 10,000 rpm isn't going to gain you any more power.

Here is a quote from Loren Duncan of Duncan Racing on CDI boxes on a 400EX.

"We’re not big fans of changing the CDI box. If you reach the point where the rev-limiter kicks in where a box would theoretically help you, your engine has already quit making power. In the low 8000 rpm range, it’s done making power. In the mid-8000 the rev-limiter should be kicking in. When you find someone that is revving it that high, they should have shifted 500 rpm earlier. It’s a rare occasion if anyone has ever told us that they felt they gained more power with a modified ignition."

Full article can be read here. (http://www.atvaction.net/ME2/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=542D400698094EFE9BE15AFEB58339F1)

[mad4106]

Thanks ish416 that was very helpful article!

[DragonGunner]

Originally posted by ish416
CDI rev boxes do what they say, they raise the limiter 1000 rpm.

You would be better off to change the gearing as your EX has already stopped making power around 8000 rpm and spinning it to 10,000 rpm isn't going to gain you any more power.

Here is a quote from Loren Duncan of Duncan Racing on CDI boxes on a 400EX.

"We’re not big fans of changing the CDI box. If you reach the point where the rev-limiter kicks in where a box would theoretically help you, your engine has already quit making power. In the low 8000 rpm range, it’s done making power. In the mid-8000 the rev-limiter should be kicking in. When you find someone that is revving it that high, they should have shifted 500 rpm earlier. It’s a rare occasion if anyone has ever told us that they felt they gained more power with a modified ignition."

Full article can be read here. (http://www.atvaction.net/ME2/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=542D400698094EFE9BE15AFEB58339F1)

An Doug Eichner ran a Duncan Racing 440EX with different CDI an modified ignition system for yrs....an won at least 2 Four Stroke Championships running against Cannondales an Raptors. Also I've seen Duncan Racing selling different ignition systems for the 400EX...just food for thought....this is out of DirtWheels magazines an articles.