400ex CDI rev box

[djwilliams0822]

I bought a 400ex and i wanted to know if it still had the stock cdi in it it sayed shindengen on it. is this a stock cdi box or an aftermarket

[CJM]

Pretty sure stock iirc. Dont waste your money on a CDI box btw, it wont help the 400 as it stops making useful power well before its redline.

[djwilliams0822]

Yea I do a lot of trail riding. You don't think it is worth it?

[CJM]

Originally posted by djwilliams0822
Yea I do a lot of trail riding. You don't think it is worth it?

I know its not worth it.

What many perceive is a power gain is nothing more than a different ignition curve. The problem is all your paying for in most cases is a XR250 cdi. The other problem is it makes it a pain to start with such a cdi b/c its designed for a kickstart bike.

Id spend my money elsewhere, such as a port and polish on the head or an 04-05 trx450r carb.

[djwilliams0822]

Ok thanks :)

[CJM]

Originally posted by djwilliams0822
Ok thanks :)

No Problem

[DragonGunner]

My White Brothers CDI was well worth the money over 10 yrs. ago an I still run it. ANYONE getting to my neck of the woods can stop by an ride it with the stock CDI, an then with the WB CDI an you will see the differance whether your balls out across a field or fast trails in the woods. Its a 406 with Web cam, ported with 3 angle valve, 11:1 ......I don't believe all the aftermarket CDI's are probably the same.....some may be better than others....mine must be one of the better ones. Mine was worth the money an I wouldn't sell it an often recommend them to others, by the way when the 400EX came out it won the Baja 1000 in its class as a 416 with a White Brothers CDI.

[dxcody]

Dragongunner, did you build your motor on your 400?

[CJM]

WB CDI is literally an XR250 CDI. Seriously if you dont believe me buy one and swap it.

Look carefully at your CDI DragonGunner, it will say shindengen. Also notice white brothers initials arent exactly laser cut in it-more like hand scribed.

Anyways heres what Mickey Dunlop said... http://www.atvriders.com/articles/askmickey1.html

3rd or 4th post down on that page.

Heres more info on it: http://www.exriders.com/vbb/showthread.php?threadid=466887&perpage=10&pagenumber=2

You guys want to spend your cash on it, go right ahead.

[atvrider13]

Even if it is "just" a xr250 box it works good on the 400ex. I like mine and also had the same results as dragon

[buck440]

placebo effect...

[2muchquad]

placebo effect...



LMAO:D :D

[Honda5]

After reading that Dunlap interview I still stand by my previous statements. They cut out the rpm limiter. If the dirt bile can use the extra rpm why don't the quad? I never did any big bore but the motors with cams and over 12.5:1 loved the aftermarket cdi. I didn't use the WB because of all the hard starting problems.
There was a reason 9 out of 10 400ex lined up on the gate had a +rpm cdi. We did 100's of holeshot practices and found that they did work.

[CJM]

Whatever you guys want to believe is fine by me, been there done that-it dont do jack. Just wait till you go to start it and your batterys a bit low and all it does is crank over and over..but wont start.. Also fact of the matter is by the time you get to that extra 1000 rpms, hell WAY before that the engine stock or modified has stopped making usable power.

If the things worked EVERYONE would put one on any quad, dirtbike, etc. Thats def not the case.

But I digress, spend your hard earned cash on it if you want.

[Honda5]

Its not only about where the motor stops building power its where in the power you are after the shift . Just guessing but you didn't do much mx racing or drag racing. The numbers don't lie.

[2muchquad]

I havent put one on my 400 yet but i may.I do know for a fact that the big gun rev box i had on my ds650 definately made a difference.The stock ds650 signed off at 7600rpm so the extra rpm really helped the motor especially since it was still makin power up top!Finally pulled the trigger on one after consulting a lot of the forums,guys liked the big gun or ron woods cdi.So some do work on certyain models.May try a good one on the 400 though;)

[steve181]

a rev box is only good for mx racing, where that extra rpm is there so you dont have to shift then downshift as much

400ex's stop making power before the rev limiter and are alot faster if they are shifted at lower rpms



listen to CJM unless your actually gunna use the extra rpm

[buck440]

i you have your quad dyno'ed and a cdi that you can adjust the power curve on then yah you get more hp in higher rpm's. these aftermarket cdi's have no idea on your mods and take a guess on where to put the curve. you may get lucky and have the right mods for it to make a differance but chances are you don't and won't make more power.

i think a lot of people just have no idea how a cdi and the power curve work really work and that's why we have these threads.