400ex Rev Box/CDI Box

[cmdr]

I was wondering what your guy's opinions are on buying a new rev box for a 400ex, the one's I have seen raise the rev limiter from 9,300 rpms to 10,300 rpms...will 1,000 rpm's really increase performance? Can you have higher shift points (I.E. more horsepower)? The new rev boxes on ebay go for around $40-$50. Thanks guys.

well the rev box and the cdi arent the same thing so im going to assume youre talking about the rev box. if so then they wont make any noticeable differnce untill you get atleast a pipe and filter,but id suggest waiting untill you get a cam and headwork done also

[enduro400rider]

NOT WORTH IT!! unless you have a highly built motor even then they are not that great unless you get a good one. the ones your talking about are crap. sure you get the xtra 1000rpms but it will make your bike a ***** to start. i wouldnt do it and you dont really get any more HP

[nowukno]

I got a SRP rev box for my old 400ex and i noticed very little if any gains. The quad still started ok but i sold it since it did hardly anything. Waste of money in my book.

[cmdr]

well I already have a K&N air filter with Outerwears pre-filter and a White Brothers E-Series slip-on and stock airbox and stock lid on. but you dont think a rev box would add much to it at all? and what is the difference between a rev box and a cdi box, I always thought they were the same.

a rev box just limits how many rpms the engine can rev to, a cdi control the ignition mapping and some other really technical stuff thats why a cdi is like 500 and a rev box is like 50 a cdi will offer bigger improvement but it isnt worth it unless you gt alot of money you just want to throw away, since you already got a pipe n stuff youd prob notice some improvement withe the rev box but youd be better off with porting and a cam btw what kind of bike is this

[greg_gorrell]

hes talking about somethign like a vortec, which, if you are racing can be pretty useful. i wouldnt call it throwing your money away since it can be a good investment, if you are into racing. but yeah, there are better improvements you can make (pipe, engine work, ect) that will add more power. the rev box just increases your rpms, which after long term use, i believe could cause premature engine wear. if your are looking for somethign go with the vortec, or other cdi boxes, i think dynatec makes one also but i heard those arent so good, but then again it might just be a rev box. i would look into it a little more and see if it would be a benefit to you.

[QuadJunkies]

I woudnt do a REv box until you have done some mods, that came straight from the mouths of the guys who makes them, I waited until I got my big bore. You also have to be careful w/ the boxes that advance your timing too, I have learned over trial and error that they can cause some havoc as well...If and when you do any motor mods and just wanta few more RPM's, I have been very pleased w/ my GT thunder Box. whatever you do.. Stay away from the WB box, I have heard nothing good about the rev box

[enduro400rider]

waste of money with the mods you have. basically all you will be doing is pointlessly over reving your motor. honda put a rev limiter on there for a reason. if your not racing you have no real need for it. my advise is do not waste your money. i would suggest a Sparks advanced timing key. they are only half the price of a rev box. you will get better throttle response and a claimed 2 hp increase. you wont get 2 hp but it will wake up your bike a little bit.

[greg_gorrell]

yeah, the only way you would need a rev box is if you are racing and hitting the rev limiter with the stock box. if you are just trail riding and have it pinned all the time then your motor is not gonna last long at all

[ULTRAVIOLET70]

I installed a White Brothers rev box on my '04 400EX. I actually did notice a difference not only in the higher rev limit but the engine does wind out faster (I assume due to the advanced ignition curve). IMO for the small amount of money it's worth it.

[rob-u/21]

Duncan Racing sells a vortec cdi but I think you have to get a fly wheel mod to make it all work.

[400exracing]

Originally posted by yzfmxer
well the rev box and the cdi arent the same thing so im going to assume youre talking about the rev box. if so then they wont make any noticeable differnce untill you get atleast a pipe and filter,but id suggest waiting untill you get a cam and headwork done also

what do u mean a cdi and rev box are u dif things every time i look them on on ebay or on google they show the same thing

[zeppelin]

well seeing that he is banned, your going to have a hard time getting an answer form him. but i think what he ment was a modded stock box, or the kind that white brothers sells. those both keep the same curveas stock and just bump the limit.