WB Rev Limiter, Wow!

I swapped my stock CDI chip with my buddies WB aftermarket chip and man what a difference. I noticed quicker acceleration throughout the bottome end. I have a few questions though before I run out and buy one.

1. What exactly is this doing to my stock engine?

2. It look's exactly the same as the stock box. Is there anyone out that can just reprogram the stock chip?

3. Any negatives against it? :confused: besides the price.:D :confused:

Well your letting your motor rev with about 1,200 more RPMs over the stock CDI.

It is actually a shorter box over than a stock one, and you can't reprogram them,,,I think it's a box out of a XR250 bike..

damage to the motor I don't know,,,I can say this,,if your not winding your motor out all the way all the time I can't see any damage. I have one in mine and yes they do make a difference but just remember to try and shift early so ya don't hold it in gear to long for the piston to blow out the side of the case.

[crday98]

get a stock xr 250 one and you will save around $50 too.it is the same thing wb sells for more cash and all they do is carve a WB on it with an etch pencil.the only problem with this rev box is that it will be harder to start in cold weather.

Yup right now I can't even get mine started without push starting it when it's cold,,,but ever since me and a buddy had to swap some of my parts to his bike to find a problem with his,, it ain't been right. so that might be part of the problem too,,,but tonight I'm putting the stock CDI back in so I'll post tomorrow if that was the problem..

[kabd69667]

So, an XR250 cdi is the exact same as the white brothers???

[Drtridr18]

how would it make the engine harder to start in cold weather if it just raises the rpm ceiling, does it advance the timing too? I don't think it does, but i'm not sure

[400exBro]

Originally posted by Rico
. I have one in mine and yes they do make a difference but just remember to try and shift early so ya don't hold it in gear to long for the piston to blow out the side of the case.
Why do you need to shift earlier or you might blow your piston out of the case....................
Do you want one so you can keep it pinned longer when you hit the rev limiter. Won t it achieve a little more speed.........
If not y do you guys buy them for...........
thanks
400exBro

P.S.- if they are any good maybe i should buy one
:rolleyes:

[crday98]

Originally posted by kabd69667
So, an XR250 cdi is the exact same as the white brothers???

no the white bros.is the exact same as the xr 250:D

Originally posted by 400exBro

Why do you need to shift earlier or you might blow your piston out of the case....................
Do you want one so you can keep it pinned longer when you hit the rev limiter. Won t it achieve a little more speed.........
If not y do you guys buy them for...........
thanks
400exBro

P.S.- if they are any good maybe i should buy one
:rolleyes:

The reason I was saying that was your allowing your motor to rev like 1,200 rpm's more than it was designed for,,,so holding the throttle open with more rpm's won't be to good for it,,,I guess basically don't wind each gear all the way out before you shift, cuz your pushin your motor harder than it needs to be.

[MOFO]

I still dont understand why people put these aftermarket CDI boxes on there stock motors. The stock engine was designed to make max power in the given RPM range that the stock CDI box is set to. When you are over rev'ing your engine, your not getting more power....if anything, you putting out less power when its over the stock "redline". If you look at a dyno chart for a stock 400EX, it actually drops in power before the redline is hit...when you go over this point its just rev'ing for nothing...If I remember right, the peak power is made around 1/2-3/4 of the RPM range....



Eric

Well I always read that it makes a big difference if added with a pipe, filter,,etc. etc..so I bought it to find out,,it did help a little but worth the money I'd say no. I'll be puttin my stocker back on and if my bike wants to start easier,,then I'll be sellin it or throwin it in the box with all my other crap I've taken off.....So I'm guessin your wantin to buy it from me Eric????:D :D

Plus when My motor gets rebuilt I'm goin back to the stocker CDI anyways I'm sure I won't need the extra 1200 rpm's with that butt kicken piston and cam in it.....yeeeee haaaaaa

What you notice is the advanced timing which a $10.00 timing key will do for you also. You will notice that you can rev. the motor out more but if you were to put it on a dyno you would see that you did not gain anything because you bypassed your peak horsepower where you should have been shifting to get more speed.

And yes it looks like stock because it is. Rev. boxes are modified stock boxes. They work off of capacitor inside. Modifications to the box allows for a different amount of discharge from the capacitors resulting in a greater discharge at a different rate thus resulting in a higher rev. limit and steeper timing curve.

[stevengates45]

Why dont you just get your box drilled out instead of buyin a new one?

[43atv]

hi everyone.my own experience with a modified cdi
is that it does work with a stock motor. i found that the motor revved out much smoother in every gear.even my buddy felt the difference.and with the modified motor i have not been able to hit the rev limiter so it works perfect.

[Leo]

Originally posted by Drtridr18
how would it make the engine harder to start in cold weather if it just raises the rpm ceiling, does it advance the timing too? I don't think it does, but i'm not sure

It's been covered in the past..

Basically (as I understand it),

The CDI needs to see a certain amount of engine speed before it will fire the coil. This is set higher on the kick-start XR to prevent engine kickback. the EX's electric starter motor spins it over just fast enough to reach this threshold in warm weather, but in cold weather it won't quite spin the motor over fast enough... (the stock EX CDI has a lower threshold).. a lot of guys get around this by leaving the stock CDI strapped to the frame, using it to warm up the motor, then the switch over to the XR/WB CDI box.

Leo

Well my bike hasnt' started in like 2 weeks,,since my back's been hurt I can't push start it. So I dug up the stocker CDI put it back on and it fired right up,,,Sooooooooooo,,,the stocker is stayin on and the WB is goin up for sale.

[knighttime]

I wonder if you could mount both CDI boxes and somehow use a toggle switch to use one for starting and the other for riding.

Ahhh, screw it, who wants to buy a WB CDI box for a cheap price? I have one.

Well what I dont' understand about the stupid things is I've had that WB CDI on for about 8 months or longer and put it on when it was cold here in KY and didn't have any problems. Then one day in the middle of the summer the damn thing starts having problems,,It seems like they would cause the hard starting from the get go,,,not wait 8 or 9 months to start showing problems,,well anyway I won't need the exta RPM's with the new motor rebuild,,and Knighttime,,you got yours done yet??

[knighttime]

But, I broke 3 cylinder head cover bolts when tightening them. I was using a torque wrench and the mofo's still broke. I think they were weakened from the heat of the engine. I still could start it, but I figured I'd buy the bolt extracter and replace all 12 6mm bolts that are in the cover so its done right and I wont have to screw with it again. I hope to break it in Wednesday night or on Turkey day.

Once I get my rear shock back from Terry,,which will probably be this week,,I'm droppin mine off to get the motor work done,,So I'd say before the months over I should have mine done. Then on with the rest of the winter projects,,,If my back lets me squat down to do anything,,,it's gotten better but still hurts like hell to lean over and tie my shoes,,so that's still not good.

You shouldn't need to use a torque wrench on the cylinder head bolts. They just need to be tight enough for a good seal. I stripped one hole myself. After rereading my manual it doesn't give a torque spec. for the 6 mm bolts only the 8mm bolt which is the bolt on the very top of the cover. You actually broke the bolts? - I figured it would strip before breaking.

[MJNOVA]

The Modified boxes WORK depending on many things. First is the engine stock or modified. If it is heavily modified they work. You can see it on a dyno run. If your motor is stock, not much of a change. The only things I noticed are 1. Hard to start in cold weather. 2. A little bit of overrev when coming into a corner that you might have shifted one gear higher only to downshift when coming out of it.

2. A stock bike WILL NOT make any more power with most of the boxes that are on the market. A stock bike has already made its peak horsepower before the stock box signs off.

3. Gearing does effect all of this though. A quad might feel faster if you shift it less. Shifting takes time in any form of racing.

4. With taller gearing the spacing increases between gears---the overrev allows the engine to hit the peak powerband when shifted, instead of falling below it----It depends on how fast the engine signs off after peak power..

Well my biggest beef over the WB CDI is if it stops the easy use of a push button starter then it ain't worth $1.00, and it doesn't make that big of a difference in power to make me wanna push start it everytime I want to ride,,anyway who the hell wants to push start a brand new 400ex,,,,,,,,,,not me. If I knew it was going to start problems starting a 400ex I would never have bought it..:mad:

[knighttime]

Originally posted by mbiigamber
You shouldn't need to use a torque wrench on the cylinder head bolts. They just need to be tight enough for a good seal. I stripped one hole myself. After rereading my manual it doesn't give a torque spec. for the 6 mm bolts only the 8mm bolt which is the bolt on the very top of the cover. You actually broke the bolts? - I figured it would strip before breaking.


Yep, as I look at my manual I c that u r 100% correct.:huh
Well, I guess I can either just let those 3 bolts go without removing them or I can try to extract the threads. Since I have already ordered new bolts overnight delivery for tomorrow, I guess I'll try to extract them. And yeah, they broke (didnt strip).

[MOFO]

Mike,


What did you set the torque wrench too? I bet those extra BUDweisers put some extra numbers in that manual...LOL :)

Yep, I also found that strange that they broke before they stripped out. Let me tell you, after spending most of friday night (5 hours) it kinda sucked when those *******s snapped. :mad:

On a lighter note, when are you going to post the "alcohol injected" pics? LOL :D



Oh, did you find any extraction tools yet? Catch ya later at pool league...

Eric